Pipeline configuration unit protocols and communication

ABSTRACT

An example method of controlling a data processing system having a cellular structure. The method includes transmitting a first configuration word to a first processing unit in the cellular structure. The method also includes processing data with the first processing unit in accordance with the first configuration word. The method also includes transmitting a second configuration word to the first processing unit. The method also includes transmitting a reconfiguration signal to the first unit, the reconfiguration signal indicating that the first unit should begin processing data in accordance with the second configuration word. If the first processing unit has completed processing data in accordance with the first configuration word prior to when the reconfiguration signal is received by the first processing unit, data may be processed by the first processing unit in accordance with the second configuration word. If the first processing unit has not completed processing data in accordance with the first configuration word, data may continue to be processed with the first processing unit in accordance with the first configuration word.

Example embodiments of the present invention include methods whichpermit efficient configuration and reconfiguration of one or morereconfigurable subassemblies by one or more configuration units (CT) athigh frequencies. An efficient and synchronized network may be createdto control multiple CTs.

A subassembly or cell may include conventional FPGA cells, bus systems,memories, peripherals and ALUs as well as arithmetic units ofprocessors. A subassembly may be any type of configurable andreconfigurable elements. For parallel computer systems, a subassemblymay be a complete node of any function, e.g., the arithmetic, memory ordata transmission functions.

The example method described here may be used in particular forintegrated modules having a plurality of subassemblies in aone-dimensional or multidimensional arrangement, interconnected directlyor through a bus system.

“Modules” may include systolic arrays, neural networks, multiprocessorsystems, processors having multiple arithmetic units and logic cells, aswell as known modules of the types FPGA, DPGA, XPUTER, etc.

For example, modules of an architecture whose arithmetic units and bussystems are freely configurable are used. An example architecture hasbeen described in German Patent 4416881 as well as PACT02, PACT08,PACT10, PACT13. This architecture is referred to below as VPU. Thisarchitecture may include any desired arithmetic cells, logic cells(including memories) or communicative (IO) cells (“PAEs”), which may bearranged in a one-dimensional or multidimensional matrix “processingarray” or “PA”. The matrix may have different cells of any design. Thebus systems may also have a cellular structure. The matrix as a whole orparts thereof may be assigned a configuration unit (CT) which influencesthe interconnections and function of the PA.

A special property of VPUs is the automatic and deadlock-freereconfiguration at run time. Protocols and methods required for havebeen described in PACT04, 05, 08, 10 and 13, the full content of whichis included here through this reference. The publication numbers forthese internal file numbers can be found in the addendum.

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Example Initial States of PAEs and Bus Protocol of the Configuration

Each PAE may be allocated states that may influence configurability.These states may be locally coded or may be managed through one or moreswitch groups, in particular the CT itself. A PAE may have at least twostates:

-   “Not configured”—In this state, the PAE is inactive and is not    processing any data and/or triggers. The PAE does not receive any    data and/or triggers, nor does it generate any data and/or triggers.    Only data and/or triggers relevant to the configuration may be    received and/or processed. The PAE is completely neutral and may be    configured. Registers for the data and/or triggers to be processed    may be initialized, in e.g., by the CT.-   “Configured”—The function and interconnection of the PAE is    configured. The PAE may process and generate data and/or triggers to    be processed. Such states may also be present repeatedly, largely    independently of one another, in independent parts of a PAE.

It will be appreciated that there may be a separation between dataand/or triggers for processing on the one hand and data and/or triggersfor configuration of one or more cells on the other hand.

During configuration, the CT may send, together with a validconfiguration word (KW), a signal indicating the configuration word'svalidity (RDY). This signal may be omitted if validity is ensured bysome other means, e.g., in the case of continuous transmission or by acode in the KW. In addition, the address of the PAE to be configured maybe coded in a KW.

According to the criteria described below and in the patent applicationsreferenced, a PAE may decide whether it can accept the KW and alter itsconfiguration or whether data processing must not be interrupted orcorrupted by a new configuration. Information regarding whether or notconfigurations are accepted may be relayed to the CT if the decision hasnot already been made there. The following protocol may be used: If aPAE accepts the configuration, it sends an acknowledgment ACK to the CT.If the configuration is rejected, a PAE will indicate this by sendingREJ (reject) to the CT.

Within the data processing elements (PAEs), a decision may be made byone or more of the elements regarding whether they can be reconfiguredbecause the data processing is concluded or whether they are stillprocessing data. In addition, no data is corrupted due to unconfiguredPAEs.

Example Approach to Deadlock Freedom and Correctness of the Data

FILMO Principle

Efficient management of a plurality of configurations, each of which maybe composed of one or more KWs and possibly additional control commandsmay be provided. The plurality of configurations may be configuredoverlappingly on the PA. When there is a great distance between the CTand the cell(s) to be configured, this may be a disadvantage in thetransmission of configurations. It will be appreciated that no data orstates are corrupted due to a reconfiguration. To ensure this, thefollowing rules, which are called the FILMO principle, may be defined:

-   a) PAEs which are currently processing data are not reconfigured. A    reconfiguration should take place only when data processing is    completely concluded or it is certain that no further data    processing is necessary. Reconfiguration of PAEs, which are    currently processing data or are waiting for outstanding data may    lead to faulty calculation or loss of data.)-   b) The status of a PAE should not change from “configured” to “not    configured” during a FILMO run. In addition to the method described    in PACT10, a special additional method which allows exceptions    (explicit/implict LOCK) is described below. A SubConf is a quantity    of configuration words to be configured jointly into the cell array    at a given time or for a given purpose. A situation may occur where    two different SubConfs (A, D) are supposed to share the same    resources, e.g., a PAE X. For example, SubConf A may chronologically    precede SubConf B. SubConf A must therefore occupy the resources    before SubConf D. If PAE X is still “configured” at the    configuration time of SubConf A, but its status changes to “not    configured” before the configuration of SubConf D, then a deadlock    situation may occur if no special measures are taken. An example    deadlock is if SubConf A can no longer configure the PAE X and    SubConf D occupies only PAE X, but the remaining resources which are    already occupied by SubConf A can perform no more configuration.    Neither SubConf A nor SubConf D can be executed. A deadlock would    occur.-   c) A SubConf should have either successfully configured or allocated    all the PAEs belonging to it or it should have received a reject    (REJ) before the following SubConf is configured. However, this is    true only if the two configurations share the same resources    entirely or in part. If there is no resource conflict, the two    SubConfs may be configured independently of one another. Even if    PAEs reject a configuration (REJ) for a SubConf, then the    configuration of the following SubConfs is performed. Since the    status of PAEs does not change during a FILMO run (LOCK, according    to section b), this ensures that no PAEs which would have required    the preceding configuration may be configured during the following    configuration. It will be appreciated that deadlock may occur if a    SubConf which is to be configured later were to allocate the PAEs to    a SubConf which is to be configured previously, e.g., because no    SubConf could be configured completely.-   d) Within one SubConf, it may be necessary for certain PAEs to be    configured or started in a certain sequence. For example, PAE may be    switched to a bus, only after the bus has also been configured for    the SubConf. Switching to a different bus may lead to processing of    false data.-   e) In the case of certain algorithms, the sequence in the    configuration of SubConf may need to correspond exactly to the    sequence of triggers arriving at the CT. For example, if the trigger    which initiates the configuration of SubConf 1 arrives before the    trigger which initiates the configuration of SubConf 3, then SubConf    1 must be configured completely before SubConf 3 may be configured.    If the order of triggers were reversed, this could lead to a    defective sequence of subgraphs, depending on the algorithm (see    PACT13).

Methods which meet most or all of the requirements listed above aredescribed in PACT05 and PACT10.

Management of the configurations, their timing and arrangement and thedesign of the respective components, e.g., the configuration registers,etc., may be used to provide the technique described here, however, andpossible improvements over known related art are described below.

To ensure that requirement e) is met as needed, the triggers received,which pertain to the status of a SubConf and a cell and/orreconfigurability, may be stored in the correct sequence by way of asimple FIFO, e.g., a FIFO allocated to the CT. Each FIFO entry includethe triggers received in a clock cycle. All the triggers received in oneclock cycle may be stored. If there are no triggers, no FIFO entry isgenerated. The CT may process the FIFO in the sequence in which thetriggers were received. If one entry contains multiple triggers, the CTmay first process each trigger individually, optionally either (I)prioritized or (ii) unprioritized, before processing the next FIFOentry. Since a trigger is usually sent to the CT only once perconfiguration, it may be sufficient to define the maximum depth of theFIFO relative to the quantity of all trigger lines wired to the CT. Asan alternative method, a time stamp protocol as described in PACT18 mayalso be used. Two basic types of FILMO are described in PACT10:

-   Separate FILMO: The FILMO may be designed as a separate memory and    may be separated from the normal CT memory which caches the SubConf.    Only KWs that could not be configured in the PA are copied to the    FILMO.-   Integrated FILMO: The FILMO may be integrated into the CT memory.    KWs that could not be configured are managed by using flags and    pointers.

Example methods, according to the present invention, may be applied toboth types of FILMO or to one type.

2.2. Example Differential Reconfiguration

With many algorithms, it may be advisable only to make minimal changesin configuration during operation on the basis of certain eventsrepresented by triggers or by time tuning without completely deletingthe configuration of the PAEs. This may apply to the wiring of the bussystems or to certain constants. For example, if only one constant is tobe changed, it may be advisable to be able write a KW to the respectivePAE without the PAE being in an “unconfigured” state, reducing theamount of configuration data to be transferred. This may be achievedwith a “differential reconfiguration” configuration mode, where the KWcontains the information “DIFFERENTIAL” either in encoded form orexplicitly in writing the KW. “DIFFERENTIAL” indicates that the KW is tobe sent to a PAE that has already been configured. The acceptance of thedifferential configuration and the acknowledgment may be inverted fromthe normal configuration; e.g., a configured PAE receives the KW andsends an ACK. An unconfigured PAE rejects the KW and sends REJ becausethe prerequisite for “DIFFERENTIAL” is a configured PAE.

There may be various approaches to performing a differentialreconfiguration. The differential reconfiguration may forced withoutregard for the data processing operation actually taking place in acell. In that case, it is desirable to guarantee accuratesynchronization with the data processing, which may be accomplishedthrough appropriate design and layout of the program. To relieve theprogrammer of this job, however, differential reconfigurability may alsobe made to depend on other events, e.g., the existence of a certainstate in another cell or in the cell that is to be partiallyreconfigured. It may be advantageous to store the configuration data,e.g., the differential configuration data, in or on the cell, e.g., in adedicated register. The register contents may be called up, depending ona certain state, and entered into the cell. This may be accomplished,for example, by switching a multiplexer.

The wave reconfiguration methods described below may also be used. Adifferential configuration may be made dependent on the results(ACK/REJ) of a configuration performed previously in the normal manner.In this case, the differential configuration may be performed only afterarrival of ACK for the previous nondifferential configuration.

An variant of synchronization of the differential configuration may beused, depending on how many different differential configurations areneeded. The differential configuration is not. prestored locally.Instead, on recognition of a certain state, e.g., the end of a datainput, a signal may be generated with a first cell, stopping the cellwhich is to be differentially reconfigured. Such a signal may be a STOPsignal. After or simultaneously with stopping data processing in thecell which is to be reconfigured differentially, a signal may be sent tothe CT, requesting differential reconfiguration of the stopped cell.This request signal for differential reconfiguration may be generatedand sent by the cell which also generates the STOP signal. The CT maythen send the data needed for differential reconfiguration to thestopped cell arid may trigger the differential reconfiguration. Afterdifferential reconfiguration, the STOP mode may be terminated, e.g., bythe CT. It will be appreciated that Cache techniques may also be used inthe differential reconfiguration method.

3. Example Function of Triggers

Triggers may be used in VPU modules to transmit simple information.Examples are listed below. Triggers may be transmitted by any desiredbus system (network), e.g., a configurable bus system. The source andtarget of a trigger may be programmed.

A plurality of triggers may be transmitted simultaneously within amodule. In addition to direct transmission from a source to a target,transmission from one source to multiple destinations or from multiplesources to one destination may also be provided.

Triggers transmissions may include:

-   -   Status information from arithmetic units (ALUs), e.g.,        -   carry        -   division by zero        -   zero        -   negative        -   underflow/overflow    -   Results of comparisons    -   n-bit information (for small n)    -   Interrupt request generated internally or externally    -   Blocking and enable orders    -   Requests for configurations

Triggers may be generated by any cells and may be triggered in theindividual cells by events. For example, the status register and/or theflag register may be used by ALUs or processors to generate triggers.Triggers may also be generated by a CT and/or an external unit arrangedoutside the cell array or the module.

Triggers may be received by any number of cells and may be analyzed inany manner. For example, triggers may be analyzed by a CT or an externalunit arranged outside the cell array or the module.

Triggers may be used for synchronization and control of conditionalexecutions and/or sequence controls in the array. Conditional executionsand sequence controls may be implemented by sequencers.

3.1. Example Semantics of Triggers

Triggers may be used for actions within PAEs, for example:

-   STEP: Execute an operation within a PAE upon receipt of the trigger.-   GO: Execute operations within a PAE upon receipt of the trigger. The    execution is stopped by STOP.-   STOP: Stop the execution started with GO; in this regard, see also    the preceding discussion of the STOP signal.-   LOCAL RESET: Stop the execution and transfer from the “allocated” or    “configured” state to the “not configured” state.-   WAVE: Stop the execution of operations and load a wave    reconfiguration from by the CT. In wave reconfiguration, one or more    PAEs may be subsequently reconfigured to run through the end of a    data packet. Then, the processing of another data packet may take    place, e.g., directly after reconfiguration, which may also be    performed as a differential reconfiguration.

For example, a first audio data packet may be processed with firstfilter coefficients; after running through the first audio data packet,a partial reconfiguration may take place, and then a different audiodata packet may be processed with a second set of filter coefficients.To do so, the new reconfiguration data, e.g., the second filtercoefficients, may be deposited in or at the cell, and thereconfiguration may be prompted automatically on recognition of the endof the first data packet without requiring further intervention of a CTor another external control unit.

Recognition of the end of the first data packet, e.g., the time when thereconfiguration is to be performed, may be accomplished by generating awave reconfiguration trigger. The trigger may be generated, for example,in a cell which recognizes a data end. Reconfiguration then may run fromcell to cell with the trigger as the cells finish processing of thefirst data packet, comparable to a “wave” running through a soccerstadium.

For example, a single cell may generate the trigger and send it to afirst cell, for to indicate to the first cell that the end of a firstpacket has been run through. This first cell to be reconfigured,addressed by the wave trigger generating cell, may also relay the wavetrigger signal simultaneously with the results derived from the lastdata of the first packet, which may be sent to one or more subsequentlyprocessing cells, sending the signal to these subsequently processingcells. The wave trigger signal may also be sent or relayed to thosecells which are not currently involved in processing the first datapacket and/or do not receive any results derived from the last data.Then the first cell to be reconfigured, which is addressed by the wavetrigger signal generating cell, is reconfigured and begins processingthe data of the second data packet. During this period of time, thesubsequent cells may still be processing the first data packet. Itshould be pointed out that the wave trigger signal generating cell mayaddress not only individual cells, but also multiple cells which are tobe reconfigured. This may result in an avalanche-like propagation of thewave configuration.

Data processing may be continued as soon as the wave reconfiguration hasbeen configured completely. In WAVE, it is possible to select whetherdata processing is continued immediately after complete configuration orwhether there is a wait for arrival of a. STEP or GO.

-   SELECT: Selects an input bus for relaying to the output. Example:    Either a bus A or a bus B may be switched to an output. The setting    of the multiplexer and thus the selection of the bus are selected by    SELECT.

Triggers are used for the following actions within CTs, for example:

-   CONFIG: A configuration is to be configured by the CT into the PA.-   PRELOAD: A configuration is to be preloaded by the CT into its local    memory. Therefore, the configuration need be loaded only upon    receipt of CONFIG. It will be appreciated that this may result in    more predictable caching.-   CLEAR: A configuration is to be deleted by the CT from its memory.

Incoming triggers may reference a certain configuration. Thecorresponding method is described below.

Semantics need not be assigned to a trigger signal in the network.Instead, a trigger may represent only a state. How this state may beutilized by a respective receiving PAE may be configured in therespective receiving PAE. For example, a sending PAE may send only itsstatus, and the receiving PAE generates the semantics valid for thereceived status. If several PAEs receive one trigger, differentsemantics may be used in each PAE, e.g., a different response may occurin each PAE. For example, a first PAE may be stopped, and a second PAEmay be reconfigured. If multiple PAEs send one trigger, the eventgenerating the trigger may be different in each PAE.

It should be pointed out that a wave reconfiguration and/or a partialreconfiguration can also take place in bus systems and the like. Apartial reconfiguration of a bus can take place, for example, inreconfiguration by sections.

3.2. Example System Status and Program Pointer

A system may include a module or an interlinked group of modules,depending on the implementation. For managing an array of PAEs, which isdesigned to include several modules in the case of a system, it may notbe necessary to know the status or program pointer of each PAE. Severalcases are differentiated below in order to explain this further:

-   -   PAEs as components not having a processor property. Such PAEs do        not need their own program pointer. The status of an individual        PAE is may be irrelevant, because only certain PAEs have a        usable status (see PACT01, where the status represented by a PAE        is not a program counter but instead is a data counter). The        status of a group of PAEs may be determined by the linking of        the states of the individual relevant PAEs. The information        within the network of triggers may represent the status.    -   PAEs as processors. These PAEs may have their own internal        program pointer and status. The information of only one PAE        which is relevant for other PAEs may-be exchanged by triggers.

The interaction among PAEs may yield a common status which may beanalyzed, e.g., in the CT, to determine how a reconfiguration is to takeplace. The analysis may include the instantaneous configuration of thenetwork of lines and/or buses used to transmit the triggers if thenetwork is configurable.

The array of PAEs (PA) may have a global status. Information may be sentthrough certain triggers to the CT. The CT may control the programexecution through reconfiguration based on these triggers. A programcounter may be omitted.

4. Example (Re)Configuration

VPU modules may be configured or reconfigured on the basis of events.These events may be represented by triggers (CONFIG) transmitted to aCT. An incoming trigger may reference a certain configuration (SubConf)for certain PAEs. The referenced SubConf may be sent to one or morePAES. Referencing may take place by using a conventional lookup systemor any other address conversion or address generation procedure. Forexample, the address of the executing configuration (SubConf) may becalculated as follows on the basis of the number of an incoming triggerif the SubConfs have a fixed length:offset+(trigger number*SubConf length).

VPU modules may have three configuration modes:

-   a) Global configuration: The entire VPU may be reconfigured if the    entire VPU is in a configurable state, e.g., unconfigured.-   b) Local configuration: A portion of the VPU may be reconfigured.    The local portion of the VPU which is to be reconfigured may need to    be in a configurable state, e.g., unconfigured.-   c) Differential configuration: An existing configuration may be    modified. PAEs to be reconfigured may need to be in a configured    state, e.g., they must be configured.

A configuration may include a set of configuration words (KWs). Eachconfiguration may be referenced by a reference number (ID), which may beunique.

A set of KWs identified by an ID is referred to below as asubconfiguration (SubConf). Multiple SubConfs, which may runsimultaneously on different PAEs, may be configured in a VPU. TheseSubConfs may be different or identical.

A PAE may have one or more configuration registers, one configurationword (KW) describing one configuration register. A KW may be assignedthe address of the PAE to be configured. Information indicating the typeof configuration may also be assigned to a KW. This information may beimplemented using various methods, e.g., flags or coding. Flags aredescribed in detail below.

4.1. Example ModuleID

For some operations, it may be sufficient for the CT to know theallocation of a configuration word and of the respective PAE to aSubConf. For more complex operations in the processing array, the ID ofthe SubConf assigned to an operation may be stored in each PAE.

An ID stored in the PA is referred to below as moduleID to differentiatethe IDs within the CTs. There are several reasons for introducingmoduleID, some of which are described here:

-   -   A PAE may be switched only to a bus which also belongs to the        corresponding SubConf. If a PAE is switched to the wrong        (different) bus, this may result in processing of incorrect        data. This problem can be solved by configuring buses prior to        PAEs, which leads to a rigid order of KWs within a SubConf. By        introducing moduleID, this pre configuration can be avoided,        because a PAE compares its stored moduleID with that of the        buses assigned to it and switches to a bus only when its        moduleID matches that of the PAE. As long as the two moduleIDs        are different, the bus connection is not established. As an        alternative, a bus sharing management can also be implemented,        as described in PACT 07.    -   PAEs may be converted to the “unconfigured” state by a local        reset signal. Local reset may originate from a PAE in the array        and not from a CT, and therefore is “local”. The signal may need        to be connected between all PAEs of a SubConf. This procedure        may become problematical when a SubConf that has not yet been        completely configured is to be deleted, and therefore not all        PAEs are connected to local reset. By using moduleID, the CT can        broadcast a command to all PAEs. PAEs with the corresponding        moduleID may change their status to “not configured”.    -   In many applications, a SubConf may be started only at a certain        time, but it may already be configured in advance. By using the        moduleID, the CT can broadcast a command to all PAEs. The PAEs        with the corresponding moduleID then start the data processing.

The moduleID may also be identical to the ID stored in the CT.

The moduleID may be written into a configuration register in therespective PAE. Since IDs may have a considerable width, e.g., more than10 bits in most cases, it may not be efficient to provide such a largeregister in each PAE. Alternatively, the moduleID of the respectiveSubConf be derived from the ID. The alternative module ID may have asmall width and may be unique. Since the number of all modules within aPA is typically comparatively small, a moduleID width of a few bits(e.g., 4 to 5 bits) may be sufficient. The ID and moduleID can be mappedbijectively on one another. In other words, the moduleID may uniquelyidentify a configured module within an array at a certain point in time.The moduleID may be issued to a SubConf before configuration so that theSubConf is uniquely identifiable in the PA at the time of execution. ASubConf may be configured into the PA multiple times simultaneously (seemacros, described below). A unique moduleID may be issued for eachconfigured SubConf for unambiguous allocation.

The transformation of an ID to a moduleID may be accomplished withlookup tables or lists. Since there are numerous conventional mappingmethods for this purpose, only one is explained in greater detail here:

A list whose length is 2^(ModuleID) contains the number of all IDsconfigured in the array at the moment, one ID being allocated to eachlist entry. The entry “0” characterizes an unused moduleID. If a new IDis configured, it must be assigned to a free list entry, whose addressyields the corresponding moduleID. The ID is entered into the list atthe moduleID address. On deletion of an ID, the corresponding list entryis reset at “0”.

It will be appreciated that other mapping methods may be employed.

4.2. Example PAE States

Each KW may be provided with additional flags which may be used to checkand control the status of a PAE:

-   CHECK: An unconfigured PAE is allocated and configured. If the    status of the PAE is “not configured,” the PAE is configured with    the KW. This procedure may be acknowledged with ACK.

If the PAE is in the “configured” or “allocated” state, the KW is notaccepted. The rejection may be acknowledged with REJ.

After receipt of CHECK, a PAE may be switched to an “allocated” state.Any additional CHECK is rejected, but data processing is not started.

-   DIFFERENTIAL: The configuration registers of a PAE that has already    been configured may be modified. If the status of the PAE is    “configured” or “allocated,” then the PAE may be modified using the    KW. This procedure may be acknowledged with ACK. If the PAE is in    the “unconfigured” state, the KW is not accepted but is acknowledged    by REJ (reject).-   GO: Data processing may be started. GO may be sent individually or    together with CHECK or DIFFERENTIAL.-   WAVE: A configuration may be linked to the data processing.

When the WAVE trigger is received, the configuration characterized withthe WAVE flag may be loaded into the PAE. If WAVE configuration isperformed before receipt of the trigger, the KWs characterized with theWAVE flag remain stored until receipt of the trigger and become activeonly with the trigger. If the WAVE trigger is received before the KWwhich has the WAVE flag, data processing is stopped until the KW isreceived.

At least CHECK or DIFFERENTIAL must be set for each KW transmitted.However, CHECK and DIFFERENTIAL are not allowed at the same time. CHECKand GO or DIFFERENTIAL and GO are allowed and will start dataprocessing.

In addition, a flag which is not assigned to any KW and is setexplicitly by the CT may also be implemented:

-   LOCK: It will be appreciated that PAE may not always switch to the    “not configured” state at will. If this were the case, the cell    could still be configured, for example, and it could be involved    with the processing of data while an attempt is being made to write    a first configuration from the FILMO memory into the cell; then the    cell terminates its activity during the additional FILMO run.    Therefore, without any additional measures, it is possible that a    second following configuration, which is stored in FILMO and may    actually be executed only after the first configuration, could    occupy this cell. This could then result in DEADLOCK situations. By    temporarily limiting the change of configurability of the cell    through the LOCK command, such a DEADLOCK can be avoided by    preventing the cell from being configurable at an unwanted time.    This locking of the cell against reconfiguration can take place in    particular either when FILMO is run through, regardless of whether    it is a cell which is in fact accessed for the purpose of    reconfiguration, or alternatively, the cell may be locked to prevent    reconfiguration by prohibiting the cell from being reconfigured for    a certain phase, after the first unsuccessful access to the cell by    a first configuration of the cell in the FILMO; this prevents    inclusion of the second configuration only in those cells which are    to be accessed with an earlier configuration.

Thus, according to the FILMO principle, a change may be allowed in FILMOonly during certain states. As discussed above, the FILMO state machinecontrols the transition to the “not configured” state through LOCK.

Depending on the implementation, the PAE may transmit its instantaneousstatus to a higher-level control unit (e.g., the respective CT) orstores it locally.

Example Transition Tables

A simple implementation of a state machine for observing the FILMOprotocol is possible without using WAVE or CHECK/DIFFERENTIAL. Only theGO flag is implemented here, a configuration being composed of KWstransmitted together with GO. The following states may be implemented:

-   Not configured: The PAE behaves completely neutrally, e.g., it does    not accept any data or triggers, nor does it send any data or    triggers. The PAE waits for a configuration. Differential    configurations, if implemented, are rejected.-   Configured: The PAE is configured and it processes data and    triggers. Other configurations are rejected; differential    configurations, if implemented, are accepted.-   Wait for lock: The PAE receives a request for reconfiguration (e.g.,    through local reset or by setting a bit in a configuration    register). Data processing may be stopped, and the PAE may wait for    cancellation of LOCK to be able to change to the “not configured”    state.

Current PAE status Event Next status not configured GO flag configuredconfigured Local Reset Trigger wait for lock wait for lock LOCK flag notconfigured

A completed state machine according to the approach described here makesit possible to configure a PAE which requires several KWs. This is thecase, for example, when a configuration which refers to severalconstants is to be transmitted, and these constants are also to bewritten into the PAE after or together with the actual configuration. Anadditional status is required for this purpose.

-   Allocated: The PAEs have been checked by CHECK and are ready for    configuration. In the allocated state, the PAE is not yet processing    any data. Other KWs marked as DIFFERENTIAL are accepted. KWs marked    with CHECK are rejected.    An Example

A corresponding transition table is shown below; WAVE is not included:

Current PAE status Event Next status not configured CHECK flag allocatednot configured GO flag configured allocated GO flag configuredconfigured Local Reset Trigger wait for lock wait for lock LOCK flag notconfigured4.2.1. Example Implementation of GO

GO may be set immediately during the configuration of a PAE togetherwith the KW in order to be able to start data processing immediately.Alternatively, GO may be sent to the respective PAEs after conclusion ofthe entire SubConf.

The GO flag may be implemented in various ways, including the examplesdescribed below:

a) Register

Each PAE may have a register which is set at the start of processing.The technical implementation is comparatively simple, but aconfiguration cycle may be required for each PAE. GO is transmittedtogether with the KW as a flag according to the previous description.

If it is important in which order PAEs of different PACs belonging toone EnhSubConf are configured, an alternative approach may be used toensure that this chronological dependence is maintained. Since there arealso multiple CTs when there are multiple PACs, the CTs may notify oneanother regarding whether all PAEs which must be configured before thenext in each PAE have already accepted their GO from the sameconfiguration.

One possibility of resolving the chronological dependencies andpreventing unallowed GOs from being sent is to reassign the KWs. Withreassignment, a correct order may ensured by FILMO. FILMO then marks,e.g., by a flag for each configuration, whether all GOs of the currentconfiguration have been accepted. If this is not the case, no additionalGOs of this configuration are sent. Each new configuration may have aninitial status indicating all GOs have been accepted.

To increase the probability that some PAEs are no longer beingconfigured during the configuration, the KWs of an at least partiallysequential configuration can be re-sorted. The re-sorting permits theconfiguration the KWs of the respective PAEs at a later point in time.Certain PAEs may be activated sooner, e.g., by rearranging the KWs ofthe respective configuration so that the respective PAEs are configuredearlier. These approaches may be used if the order of the KWs is notalready determined completely by time dependencies that must bemaintained after resorting.

b) Wiring by Conductor

As is the case in use of the local reset signal, PAEs may be combinedinto groups which are to be started jointly. Within this group, all PAEsare connected to a line for distribution of GO. If one group is to bestarted, GO is signaled to a first PAE. The signalling may beaccomplished by sending a signal or setting a register (see a)) of thefirst PAE. From the first PAE, GO may be relayed to the other PAEs. Oneconfiguration cycle may be necessary for starting. For relaying, alatency time may be needed to bridge great distances.

c) Broadcast

An alternative to a) and b) offers a high performance (only oneconfiguration cycle) with a comparatively low complexity.

All modules may receive a moduleID which may be different from theSubConfID.

It will be appreciated that it may be desirable to keep the size of themoduleID as small as possible. A width of a few bits (3 to 5) may besufficient. The use of moduleID is explained in greater detail below.

During configuration, the corresponding moduleID may be written to eachPAE.

GO is then started by a broadcast, by sending the moduleID together withthe GO command to the array. The command is received by all PAEs, but isexecuted only by the PAEs having the proper moduleID.

4.2.2. Locking the PAE Status

The status of a PAE may need to be prevented from changing from“configured” to “not configured” within a configuration or a FILMO run.Example: Two different SubConfs (A, D) share the same resources, inparticular, a PAE X. In FILMO, SubConf

A precedes SubConf D in time. SubConf A must therefore occupy theresources before SubConf D. PAE X is “configured” at the configurationtime of SubConf A, but it changes its status to “not configured” beforethe configuration of SubConf D. This may result in a deadlock situation,because now SubConf A can no longer configure PAE X, but SubConf D canno longer configure the remaining resources which are already occupiedby SubConf A. Neither SubConf A nor SubConf D can be executed. Asmentioned previously, LOCK may ensure that the status of a PAE does notchange in an inadmissible manner during a FILMO run. For the FILMOprinciple it is irrelevant how the status is locked. Several possiblelocking approaches are discussed below:

Basic LOCK

Before beginning the first configuration and with each new run of FILMO,the status of the PAEs is locked. After the end of each run, the statusis released again. Thus, certain changes in status may be allowed onlyonce per run.

Explicit LOCK

The lock signal is set only after the first REJ from the PA since thestart of a FILMO run. This is possible because previously all the PAEscould be configured and thus already were in the “unconfigured” state.Only a PAE which generates a REJ could change its status from“configured” to “not configured” during the additional FILMO run. Adeadlock could occur only after this time, namely when a first KWreceives a REJ and a later one is configured. However, the transitionfrom “configured” to “not configured” is prevented by immediatelysetting LOCK after a REJ. With this approach, during the first runphase, PAEs can still change their status, which means that they canchange to the “unconfigured” state. If a PAE thus changes from“configured” to “not configured” during a run before a failedconfiguration attempt, their it can be configured in the sameconfiguration phase.

Implicit LOCK

A more efficient extension of the explicit LOCK is the implicit handlingof LOCK within a PAE.

In general, only PAEs which have rejected (REJ) a configuration may beaffected by the lock status. Therefore, it is sufficient during a FILMOrun to lock the status only within PAEs that have generated a REJ. Allother PAEs may remain unaffected. LOCK is no longer generated by ahigher-level instance (CT). Instead, after a FILMO run, the lock statusin the respective PAEs may be canceled by a FREE signal. FREE can bebroadcast to all PAEs directly after a FILMO run and can also bepipelined through the array.

Example Extended Transition Tables for Implicit LOCK;

A reject (REJ) generated by a PAE may be stored locally in each PAE(REJD=rejected). The information is deleted only on return after “notconfigured.”

Current PAE status Event Next status not configured CHECK flag Allocatednot configured GO flag Configured allocated GO flag Configuredconfigured Local reset trigger Wait for free and reject (REJD)configured Local reset trigger not configured and no reject (not REJD)wait for free FREE flag not configured

It will be appreciated that the transition tables are given as examplesand that other approaches may be employed.

4.2.3. Example Configuration of a PAE

An example configuration sequence is described again in this sectionfrom the standpoint of the CT. A PAE shall also be considered to includeparts of a PAE if they manage the states described previously,independently of one another.

If a PAE is to be reconfigured, the first KW may need to set the CHECKflag to check the status of the PAE. A configuration for a PAE isconstructed so that either (a) only one KW is configured:

CHECK DIFFERENTIAL GO KW X — * KW0or (b) multiple KWs are configured, with CHECK being set with the firstKW and DIFFERENTIAL being set with all additional KWs.

CHECK DIFFERENTIAL GO KW X — — KW0 — X — KW1 — X — KW2 — X * KWn (X)set, (—) not set, GO is optional (*).

If CHECK is rejected (REJ), no subsequent KW with a DIFFERENTIAL flag issent to the PAE. After CHECK is accepted (ACK), all additional CHECKsare rejected until the return to the state “not configured” and the PAEis allocated for the accepted SubConf. Within this SubConf, the next KWsmay be configured exclusively with DIFFERENTIAL. It will be appreciatedthat this is allowed because it is known by CHECK that this SubConf hasaccess rights to the PAE.

4.2.4. Resetting to the Status “Not Configured”

With a specially designed trigger (e.g., local reset), a signal whichtriggers local resetting of the “configured” state to “not configured”is triggered in the receiving PAEs. This occurs, at the latest, after aLOCK or FREE signal is received. Resetting may also be triggered byother sources, such as a configuration register.

Local reset can be relayed from the source generating the signal overall existing configurable bus connections, e.g., all trigger buses andall data buses, to each PAE connected to the buses. Each PAE receiving alocal reset may in turn relay the signal over all the connected buses.

However, it may be desirable to prevent the local reset trigger frombeing relayed beyond the limit of a local group. Each cell may beindependently configured. Each cell configuration may indicate whetherand over which connected buses the local reset is to be relayed.

4.2.4.1. Deleting an Incompletely Configured SubConf

It may be found that the SubConf is not needed during configuration of aSubConf. For example, local reset may not change the status of all PAEsto “not configured” because the bus has not yet been completelyestablished. Two alternative approaches are proposed. In bothapproaches, the PAE which would have generated the local reset sends atrigger to the CT. Then the CT informs the PAEs as follows:

4.2.4.2. When Using moduleID

If a possibility for storage of the moduleID is provided within eachPAE, then each PAE can be requested to go to the status “not configured”with this specific ID. This may be accomplished with a simple broadcastin which the ID is also sent.

4.2.4.3. When Using the GO Signal

If a GO line is wired in exactly the order in which the PAEs areconfigured, a reset line may be assigned to the GO line. The reset linemay set all the PAEs in the state “not configured.”

4.2.4.4. Explicit Reset by the Configuration Register

In each PAE, a bit or a code may be defined within the configurationregister. When this bit or code is set by the CT, the PAE is reset inthe state “not configured.”

4.3. Holding the Data in the PAEs

It is advantageous to hold the data and states of a PAE beyond areconfiguration. Data stored within a PAE may be preserved despitereconfiguration. Appropriate information in the KWs, may define for eachrelevant register whether the register is reset by the reconfiguration.

Example

For example, if a bit within a KW is logical 0, the current registervalue of the respective data register or status register may beretained. A logical 1 resets the value of the register. A correspondingKW may then have the following structure:

Input register Output register Status flags A B C H L equal/ overflowzero

Whether or not the data will be preserved, may then be selected witheach reconfiguration.

4.4. Setting Data in the PAEs

Date may be written into the registers of the PAEs duringreconfiguration of the CT. The relevant registers may be addressed byKWs. A separate bit may indicate whether the data is to be treated as aconstant or as a data word.

-   -   A constant may be retained until it is reset.    -   A data word may be valid for precisely a certain number of        counts, e.g., precisely one count. After processing the data        word, the data word written to the register by the CT may no        longer exist.        5. Example Extensions

The bus protocol may be extended by also pipelining the KWs and ACK/REJsignals through registers.

One KW or multiple KWs may be sent in each clock cycle. The FILMOprinciple may be maintained. An allocation to a KW may be written to thePA in such a way that the delayed acknowledgment is allocatedsubsequently to the KW. KWs depending on the acknowledgment may bere-sorted so that they are processed only after receipt of theacknowledgment.

Several alternative approaches are described below:

5.1. Example Lookup Tables (STATELUT)

Each PAE may send its status to a lookup table (STATELUT). The lookuptable may be implemented locally in the CT. In sending a KW, the CT maycheck the status of the addressed PAE via a lookup in the STATELUT. Theacknowledgment (ACK/REJ) may be generated by the STATELUT.

In a CT, the status of each individual PAE may be managed in a memory ora register set. For each PAE there is an entry indicating in which mode(“configured,” “not configured”) the PAE is. On the basis of this entry,the CT checks on whether the PAE can be reconfigured. This status ischecked internally by the CT, e.g., without checking back with the PAEs.Each PAE sends its status independently or after a request, depending onthe implementation, to the internal STATELUT within the CT. When LOCK isset or there is no FREE signal, no changes in status are sent by thePAEs to the STATELUT and none are received by the STATELUT.

The status of the PAEs may be monitored by a simple mechanism, with themechanisms of status control and the known states that have already beendescribed being implemented.

Setting the “Configured” Status

When writing a KW provided with a CHECK flag, the addressed may bemarked as “allocated” in the STATELUT.

-   -   When the PAE is started (GO), the PAE may be entered as        “configured.”        Resetting the “Configured” Status to “not Configured”

Several methods may be used, depending on the application andimplementation:

-   a) Each PAE may send a status signal to the table when the PAEs'    status changes from “configured” to “not configured.” This status    signal may be sent pipelined.-   b) A status signal (local reset) may be sent for a group of PAEs,    indicating that the status for the entire group has changed from    “configured” to “not configured”. All the PAEs belonging to the    group may be selected according to a list, and the status for each    individual PAE may be changed in the table. The status signal may    need to be sent to the CT from the last PAE of a group removed by a    local reset signal. Otherwise, there may be inconsistencies between    the STATELUT and the actual status of the PAEs. For example, the    STATELUT may list a PAE as “not configured” although it is in fact    still in a “configured” state.-   c) After receipt of a LOCK signal, possibly pipelined, each PAE    whose status has changed since the last receipt of LOCK may send its    status to the STATELUT. LOCK here receives the “TRANSFER STATUS”    semantics. However, PAEs transmit their status only after this    request, and otherwise the status change is locked, so the approach    remains the same except for the inverted semantics.

To check the status of a PAE during configuration, the STATELUT may bequeried when the address of the target PAE of a KW is sent. An ACK orREJ may be generated accordingly. A KW may be sent to a PAE only if noREJ has been generated or if the DIFFERENTIAL flag has been set.

This approach ensures the chronological order of KWs. Only valid KWs aresent to the PAEs. One disadvantage here is the complexity of theimplementation of the STATELUT and the resending of the PAE states tothe STATELUT. Bus bandwidth and running time may also be required forthis approach.

5.2. Example Re-sorting the KWs

The use of the CHECK flag for each first KW (KW1) sent to a PAE may beneeded in the following approach.

The SubConf may be resorted as follows:

-   -   1. First, KW1 of a first PAE may be written. In the time (DELAY)        until the receipt of the acknowledgment (ACK/REJ), there follow        exactly as many dummy cycles (NOPs) as cycles have elapsed.    -   2. Then the KW1 of a second PAE may be written. During DELAY the        remaining KWs of the first PAE may be written. Any remaining        cycles are filled with dummy cycles. The configuration block        from KW1 until the expiration of DELAY is referred to here as an        “atom”.    -   3. The same procedure may be followed with each additional PAE.    -   4. If more KWs are written for a PAE than there are cycles        during DELAY, the remaining portion may distributed among the        following atoms. As an alternative, the DELAY may also be        actively lengthened, so a larger number of KWs may be written in        the same atom.

Upon receipt of ACK for a KW1, all additional KW1s for the correspondingPAE may be configured. If the PAE acknowledges this with REJ, no otherKW pertaining to the PAE may be configured.

This procedure guarantees that the proper order will be maintained inconfiguration.

A disadvantage of this approach is that the optimum configuration speedmay not be achieved. To maintain the proper order, the waiting time ofan atom may optionally have to be filled with dummy cycles (NOPs), sothe usable bandwidth and the size of a SubConf are increased by theNOPs.

This restriction on the configuration speed may be difficult to avoid.To minimize the amount of configuration data and configuration cycles,the number of configuration registers may need to be minimized. Athigher frequencies, DELAY necessarily becomes larger, so this collideswith the requirement that DELAY be used appropriately by filling up withKW.

Therefore, approach is most appropriate for use in serial transmissionof configuration data. Due to the serialization of KWs, the data streamis long enough to fill up the waiting time.

5.3. Analyzing the ACK/REJ Acknowledgment with Latency (CHECK, ACK/REJ)

The CHECK signal may be sent to the addressed PAE with the KWs over oneor more pipeline stages. The addressed PAE acknowledges (ACK/REJ) thisto the CT, also pipelined.

In each cycle, a KW may be sent. The KW's acknowledgment (ACK/REJ) isreceived by the CT n cycles later. The KW and its acknowledgment may beanalyzed. However, during this period of time, no additional KWs aresent. This results in two problem areas:

-   -   Controlling the FILMO    -   Maintaining the sequence of KWs        5.3.1. Controlling the FILMO Within the FILMO, it must be noted        which KWs have been accepted by a PAE (ACK) and which have been        rejected (REJ). Rejected KWs may be sent again in a later FILMO        run. In this later run, it may be more efficient to run through        only the KWs that have been rejected.

The requests described here may be implemented as follows: Anothermemory (RELJMP) which has the same depth as the FILMO may be assigned tothe FILMO. A first counter (ADR_CNT) points to the address in the FILMOof the KW currently being written into the PAE array. A second counter(ACK/REJ_CNT) points to the position in the FILMO of the KW whoseacknowledgment (ACK/REJ) is currently returning from the array. Aregister (LASTREJ) stores the value of ACK/REJ_CNT which points to theaddress of the last KW whose configuration was acknowledged with REJ. Asubtractor calculates the difference between ACK/REJ_CNT and LASTREJ. Onoccurrence of a REJ, this difference is written into the memory locationhaving the address LASTREJ in the memory RELJMP.

RELJMP thus contains the relative jump width between a rejected KW andthe following KW.

-   -   1. A RELJMP entry of “0” (zero) is assigned to each accepted KW.    -   2. A RELJMP entry of “>0”, (greater than zero) is assigned to        each rejected KW. The address of the next rejected KW is        calculated in the FILMO by adding the current address having the        RELJMP entry.    -   3. A RELJMP entry of “0” (zero) is assigned to the last rejected        KW, indicating the end.

The memory location of the first address of a SubConf is occupied by aNOP in the FILMO. The associated RELJMP contains the relative jump tothe first KW to be processed.

-   -   1. In the first run of the FILMO, the value is “1” (one).    -   2. In a subsequent run, the value points to the first KW to be        processed, so it is “>0” (greater than zero).    -   3. If all KWs of the SubConf have been configured, the value is        “0” (zero), by which the state machine determines that the        configuration has been completely processed.

It will be appreciated that other approaches to coding variousconditions may be employed.

5.3.2. Observing the Sequence (BARRIER)

The method described in section 5.3, may not guarantee a certainconfiguration sequence. This method only ensures the FILMO requirementsaccording to 2.1 a)-c).

In certain applications, it is relevant to observe the configurationsequence within a SubConf (2.1 e)) and to maintain the configurationsequence of the individual SubConfs themselves (2.1 d)).

Observing sequences may be accomplished by partitioning SubConf intomultiple blocks. A token (BARRIER) may be inserted between individualblocks, and can be skipped only if none of the preceding KWs has beenrejected (REJ).

If the configuration reaches a BARRIER, and REJ has occurred previously,the BARRIER must not be skipped. A distinction is made between at leasttwo types of barriers:

-   a) Nonblocking: The configuration is continued with the following    SubConf.-   b) Blocking: The configuration is continued with additional runs of    the current SubConf. BARRIER is not skipped until the current    SubConf has been configured completely.    Optimizing Configuration Speed.

Considerations on optimization of the configuration speed: It is notnormally necessary to observe the sequence of the configuration of theindividual KWs. However, the sequence of activation of the individualPAEs (GO) may need to be observed exactly. The speed of theconfiguration can be increased by re-sorting the KWs so that all the KWsin which the GO flag has not been set are pulled before the BARRIER.Likewise, all the KWs in which the CHECK flag has been set may need tobe pulled before the BARRIER. If a PAE is configured with only one KW,the KW may need to be split into two words, the CHECK flag being setbefore the BARRIER and the GO flag after the BARRIER.

At the BARRIER it is known whether all CHECKS have been acknowledgedwith ACK. Since a reject (REJ) occurs only when the CHECK flag is set,all KWs behind the barrier are may be executed in the correct order. TheKWs behind the barrier may be run through only once, and the start ofthe individual PAEs occurs properly.

5.3.3. Garbage Collector

Two different implementations of a garbage collector (GC) are suggestedfor the approach described in to 5.3.

-   a) A GC may be implemented as an algorithm or a simple state    machine: At the beginning, two pointers point to the starting    address of the FILMO: a first pointer (read pointer) points to the    current KW to be read by the GC, and a second pointer (write    pointer) points to the position to which the KW is to be written.    Read pointer is incremented linearly. Each KW whose RelJmp is not    equal to “0” (zero) is written to the write pointer address. RelJmp    is set at “1” and write pointer is incremented.-   b) The GC may be integrated into the FILMO by adding a write pointer    to the readout pointer of the FILMO. At the beginning of the FILMO    run, the write pointer points to the first entry. Each KW that has    been rejected with a REJ in configuration of a PAE is written to the    memory location to which the write pointer points. Then write    pointer is incremented. An additional FIFO-like memory (e.g.,    including a shift register) may be needed to temporarily store the    KW sent to a PAE in the proper order until the ACK/REJ belonging to    the KW is received by the FILMO again. Upon receipt of an ACK, the    KW may be ignored. Upon receipt of REJ, the KW may be written to the    memory location to which the write pointer is pointing (as described    above). Here, the memory of the FILMO may be designed as a multiport    memory. In this approach, there is a new memory structure at the end    of each FILMO run, with the unconfigured KWs standing in linear    order at the beginning of the memory. No additional GC runs may be    necessary. Implementation of RelJmp and the respective logic may be    completely omitted.    5.4. Prefetching of the ACK/REJ Acknowledgment with Latency

Alternative to 5.3 may be used. The disadvantage of this alternativeapproach is the comparatively long latency time, corresponding to threetimes the length of the pipeline.

The addresses and/or flags of the respective PAEs to be configured maybe sent on a separate bus system before the actual configuration. Thetiming may be designed so that at the time the configuration word is tobe written into a PAE, its ACK/REJ information is available. Ifacknowledged with ACK, the CONFIGURATION may be performed; in the caseof a reject (REJ), the KWs are not sent to the PAE (ACK/REJ-PREFETCH).FILMO protocol, in particular LOCK, ensures that there will be nounallowed status change of the PAEs between ACK/REJ-PREFETCH andCONFIGURATION.

5.4.1. Structure of FILMO

FILMO may function as follows: KWs may be received in the correct order,either (i) from the memory of the CT or (ii) from the FILMO memory.

The PAE addresses of the KWs read out may be sent to the PAEs, pipelinedthrough a first bus system. The complete KWs may be written to aFIFO-like memory having a fixed delay time (e.g., a shift register).

The respective PAE addressed may acknowledges this by sending ACK orREJ, depending on the PAE's status. The depth of the FIFO corresponds tothe number of cycles that elapse between sending the PAE address to aPAE and receipt of the acknowledgment of the PAE. The cycle from sendingthe address to a PAE until the acknowledgment of the PAE is received isknown as prefetch.

Due to the certain delay in the FIFO-like memory, which is not identicalto FILMO here, the acknowledgment of a PAE may be received at the CTexactly at the time when the KW belonging to the PAE appears at theoutput of the FIFO. Upon receipt of ACK, the KW may be sent to the PAE.Here, no acknowledgment is expected. The PAE status has not changed inan admissible manner in the meantime, so that acceptance is guaranteed.

Upon receipt of REJ, the KW is not sent to the PAE but instead may bewritten back into the FILMO memory. An additional pointer is availablefor this, which points to the first address at the beginning of linearreadout of the FILMO memory. The counter may be incremented with eachvalue written back to the memory. In this way, rejected KWs areautomatically packed linearly, which corresponds to an integratedgarbage collector run (see also 5.3).

5.4.2. Sending and Acknowledging Over a Register Pipeline

The approach described here may be used to ensure a uniform clock delaybetween messages sent and responses received if different numbers ofregisters are connected between one transmitter and multiple possiblereceivers of messages. One example of this would be if receivers arelocated at different distances from the transmitter. The message sentmay reach nearby receivers sooner than more remote receivers.

To achieve the same transit time for all responses, the response is notsent back directly by the receiver. Instead the response is sentfurther, to the receiver at the greatest distance from the sender. Thispath must have the exact number of receivers so that the response willbe received at the time when a response sent simultaneously with thefirst message would be received at this point. From here out, the returntakes place exactly as if the response were generated in this receiverat the greatest distance from the sender.

It will be appreciated that it does not matter here whether the responseis actually sent to the most remote receiver or whether it is sent toanother chain having registers with the same time response.

6. Hierarchical CT Protocol

As described in PACT10, VPU modules may be scalable by constructing atree of CTs, the lowest CTs (low-level CTs) of the PAs being arranged onthe leaves. A CT together with the PA assigned to the CT is known as aPAC. In general, any desired data or commands may be exchanged betweenCTs. Any technically appropriate protocol can be used for this purpose.

However, if the communication (inter-CT communication) causes SubConf tostart on various low-level CTs within the CT tree (CTTREE), therequirements of the FILMO principle should be ensured to guaranteefreedom from deadlock.

In general, two cases are to be distinguished:

-   1. In the case a low-level CT, the start of a SubConf may be    requested. The SubConf may run only locally on the low-level CT and    the PA assigned the low-level CT. This case can be processed at any    time within the CTTREE and does not require any special    synchronization with other low-level CTs.-   2. In the case of a low-level CT, the start of a configuration may    be requested. The SubConf may run on multiple low-level CTs and the    PAs assigned to them. In this case, it is important to be sure that    the configuration is called up “atomically” or invisibly on all the    CTs involved. This may be accompanied by ensuring that no other    SubConf is started during call-up and start of a given SubConf. Such    a protocol is known from PACT10. However, a protocol that is even    more optimized is desirable.

The protocol described in PACT10 may be inefficient as soon as apipelined transmission at higher frequencies is necessary. This isbecause bus communication is subject to a long latency time.

An alternative approach is described in the following sections.

A main function of inter-CT communication is to ensure that SubConfsinvolving multiple PACs are started without deadlock. Enhancedsubconfiguration (“EnhSubConfs”) are SubConfs that are not just executedlocally on one PAC but instead may be distributed among multiple PACs.An EnhSubConf may include multiple SubConfs, each started by way oflow-level CTs. A PAC may include a PAE group having at least one CT.

In order for multiple EnhSubConfs to be able to run on identical PACswithout deadlock, a prioritization of their execution may be defined bya suitable mechanism (for example, within the CTTREE). If SubConfs areto be started from multiple different EnhSubConfs running on the samePACs, then these SubConfs may be started on the respective PACs in achronological order corresponding to their respective priorities.

Example: Two EnhSubConfs are to be started, namely EnhSubConf-A on PACs1, 3, 4, 6 and EnhSubConf-B on PACs 3, 4, 5, 6. It is important toensure that EnhSubConf-A is always configured on PACs 3, 4 and 6exclusively either before or after EnhSubConf-B. For example, ifEnhSubConf-A is configured before EnhSubConf-B on PACs 3 and 4, and ifEnhSubConf-A is to be configured on PAC 6 after EnhSubConf-B, a deadlockoccurs because EnhSubConf-A could not be started on PAC 6, andEnhSubConf-B could not be started on PACs 3 and 4. Such a case isreferred to below as crossed or a cross.

To prevent deadlock, it is sufficient to prevent EnhSubConfs fromcrossing. If there is an algorithmic dependence between two EnhSubConfs,e.g., if one EnhSubConf must be started after the other on the basis ofthe algorithm, this is normally resolved by having one EnhSubConf startthe other.

Example Protocol

Inter-CT communication may distinguish two types of data:

-   a) a SubConf containing the configuration information,-   b) an ID chain containing a list of IDs to be started, together with    the information regarding on which PAC the SubConf referenced by the    ID is to be started. One EnhSubConf may be translated to the    individual SubConfs* to be executed by an ID chain: ID_(EnhSubConf)}    ID chain {PAC₁: ID_(SubConf1)), (PAC₂:ID_(SubConf2)),    (PAC₃:ID_(SubConf3)), . . . (PAC_(n): ID_(SubConfn))}

Inter-CT communication may differentiate between the followingtransmission modes:

-   REQUEST: The start of an EnhSubConf may be requested by a low-level    CT from the higher-level CT, or by a higher-level CT from another CT    at an even higher level. This is repeated until reaching a CT which    has stored the ID chain or reaching the root CT, which always has    the ID chain in memory.-   GRANT: A higher-level CT orders a lower-level CT to start a SubConf.    This may be either a single SubConf or multiple SubConfs, depending    on the ID chain.-   GET: A CT requests a SubConf from a higher-level CT by sending the    proper ID. If the higher-level CT has stored (cached) the SubConf,    it sends this to the lower-level CT; otherwise, it requests the    SubConf from an even higher-level CT and sends it to the lower-level    CT after receipt. At the latest, the root CT SubConf will have    stored the SubConf.-   DOWNLOAD: Loading a SubConf into a lower-level CT.-   REQUEST activates the CTTREE either until reaching the root CT, the    highest CT in the CTTREE, or until a CT in the CTTREE has stored the    ID chain. The ID chain may only be stored by a CT which contains all    the CTs included in the list of the ID chain as leaves or branches.    In principle, the root CT (e.g., CTR, as describe in PACT10) has    access to the ID chain in its memory. GRANT is then sent to all CTs    listed in the ID chain. GRANT is sent “atomically.” All the branches    of a CT may receive GRANT either simultaneously or sequentially but    without interruption by any other activity between one of the    respective CTs and any other CT which could have an influence on the    sequence of the starts of the SubConfs of different EnhSubConfs on    the PACs. A low-level CT which receives a GRANT may configure the    corresponding SubConf into the PA immediately. The configuration may    occur without interruption. Alternatively the SubConf may write into    FILMO or into a list which gives the configuration sequence. This    sequence may be needed to prevent a deadlock. If the SubConf is not    already stored in the low-level CT, the low-level CT may need to    request the SubConf using GET from the higher-level CT. Local    SubConfs (SubConfs that are not called up by an EnhSubConf but    instead concern only the local PA) may be configured or loaded into    FILMO between GET and the receipt of the SubConf (DOWNLOAD) if    allowed or required by the algorithm. SubConfs of another EnhSubConf    started by a GRANT received later may be started only after receipt    of DOWNLOAD, as well as configuration and loading into FILMO.

Examples of the structure of SubConf have been described in patentapplications PACT05 and PACT10.

The approach discussed here includes separate handling of call-up ofSubConf by ID chains. An ID chain is a SubConf having the followingproperty:

Individual SubConfs may be stored within the CTTREE, e.g., by cachingthem. A SubConf need not be reloaded completely, but instead may be sentdirectly to the lower-level CT from a CT which has cached thecorresponding SubConf. In the case of an ID chain, all the lower-levelCTs may need to be loaded from a central CT according to the protocoldescribed previously. It may be efficient if the CT at the lowest levelin the CTTREE, which still has all the PACs listed in the ID chain asleaves, has the ID chain in its cache. CTs at an even lower level mayneed to not store anything in their cache, because they are no longerlocated centrally above all the PACs of the ID chain. Higher-level CTsmay lose efficiency because a longer communication link is necessary. Ifa request reaches a CT having a complete ID chain for the EnhSubConfrequested, this CT may trigger GRANTs to the lower-level CTs involved.The information may be split out of the ID chain so that at least thepart needed in the respective branches is transmitted. To preventcrossing in such splitting, it may be necessary to ensure that the nextCT level will also trigger all GRANTs of its part of the EnhSubConfwithout being interrupted by GRANTs of other EnhSubConfs. One approachto implementing this is to transmit the respective parts of the ID chain“atomically.” To control the caching of ID chains, it may be useful tomark a split ID chain with a “SPLIT” flag, for example, during thetransmission.

An ID chain may be split when it is loaded onto a CT which is no longerlocated centrally within the hierarchy of the CTTREE over all the PACsreferenced within the ID chain. In this case, the ID chain may no longerbe managed and cached by a single CT within the hierarchy. Multiple CTsmay process the portion of the ID chain containing the PACs which areleaves of the respective CT. A REQUEST may need to be relayed to a CTwhich manages all the respective PACs. It will be appreciated that thefirst and most efficient CT in terms of hierarchy (from the standpointof the PACs) which can convert REQUEST to GRANT may be the first CT inascending order, starting from the leaves, which has a complete, unsplitID chain. Management of the list having allocations of PAC to ID doesnot require any further explanation. The list can be processed either bya program running within a CT or it may be created from a series ofassembler instructions for controlling lower-level CTs.

A complete ID chain may then have the following structure:ID_(EnhSubConf)} ID chain{SPLIT, (PAC₁:ID_(SubConf1)), (PAC₂:ID_(SubConf2)), (PAC₃:ID_(SubConf3)) . . . (PAC_(n):ID_(SubConfn))}

6.1. Example Procedure for Precaching SubConfs

Within the CTTREE, SubConfs may be preloaded according to certainconditions, e.g., the SubConfs may be cached before they are actuallyneeded. This method may greatly improve performance within the CTTREE.

A plurality of precache requests may be provided. These may include:

-   a) A load request for an additional SubConf may be programmed within    a SubConf being processed on a low-level CT.-   b) During data processing within the PA, a decision may be made as    to which SubConf is to be preloaded. The CT assigned to the PA may    be requested by a trigger. Accordingly, the trigger may be    translated to the ID of a SubConf within the CT, to preload a    SubConf. It may also be possible for the ID of a SubConf to be    calculated in the PA or to be configured in advance in the PA. The    message to the assigned CT may contain the ID directly.

The SubConf to be loaded may be cached without being started. The startmay take place at the time when the SubConf would have been startedwithout prior caching. The difference is that at the time of the startrequest, the SubConf is already stored in the low-level CT or one of themiddle-level CTs and either may be configured immediately or may beloaded very rapidly onto the low-level CT and then started. This mayeliminate a time-consuming run-through of the entire CTTREE.

A compiler, which generates the SubConf, makes it possible to decidewhich SubConf is to be cached next. Within the program sequence graphs,it may be possible to see which SubConfs could be executed next. Theseare then cached. The program execution decides in run time which of thecached SubConfs is in fact to be started.

A preloading mechanism may be provided which removes the cached SubConfto make room in the memory of the CT for other SubConfs. Likeprecaching, deletion of certain SubConfs by the compiler can bepredicted on the basis of program execution graphs.

Mechanisms for deletion of SubConfs as described in PACT10, (e.g., theone configured last, the one configured first, the one configured leastoften (see PACT10)) may be provided in the CTs in order to manage thememory of the CT accordingly. It will be appreciated that not onlyexplicitly precached SubConfs can be deleted, but also any SubConf in aCT memory generally be deleted. If the garbage collector has alreadyremoved a certain SubConf, the explicit deletion becomes invalid and maybe ignored.

An explicit deletion can be brought about through a command which may bestarted by any SubConf. This includes any CT within the tree, its own CTor explicit deletion of the same SubConf (e.g., deletion of its ownSubconf in which the command stands, in which case correct terminationmust be ensured).

Another possibility of explicit deletion is to generate, on the basis ofa certain status within the PAs, a trigger which is relayed to the CTand analyzed as a request for explicit deletion.

6.2. Interdependencies Among PAEs

For the case when the sequence in which PAEs of different PACs belongingto one EnhSubConf are configured is relevant, an alternative proceduremay be provided to ensure that this chronological dependence ismaintained. Since there may be multiple CTs in the case of multiplePACs, these CTs may exchange information to determine whether all PAEswhich must be configured before the next PAE in each PAC have alreadyaccepted their GO from the same configuration. One possibility ofbreaking up the time dependencies and preventing unallowed GOs frombeing sent is to exchange the exclusive right to configuration among theCTs. The KWs may be recognized so that a correct order is ensuredthrough the sequence of their configurations and the transfer of theconfiguration rights. Depending on how strong the dependencies are, itmay be sufficient if both CTs configure their respective PA in parallelup to a synchronization point. The CTs may then wait for one another andcontinue configuring in parallel until the next synchronization point.Alternatively, if no synchronization point is available, the CTs maycontinue configuring in parallel until the end of the EnhSubConf.

7. Example SubConf Macros

It will be appreciated that caching of SubConf may be especiallyefficient if as many SubConfs as possible can be cached. Efficient useof caching may be particularly desirable with high-level languagecompilers, because compilers often generate recurring routines on anassembler level, e.g., on a SubConf level in VPU technology.

In order to maximize reuse of SubConf, special SubConf macros (SubConfM)having the following properties may be introduced:

-   -   no absolute PAE addresses are given; instead a SubConf is a        prelaid-out macro which uses only relative addresses;    -   application-dependent constants are transferred as parameters.

With a special SubConf macros, the absolute addresses are not calculateduntil the time when the SubConf is loaded into the PA. Parameters may bereplaced by their actual values. To do so, a modified copy of theoriginal special SubConf may be created so that either (I) this copy isstored in the memory of the CT (integrated FILMO) or (ii) it is writtenimmediately to the PA, and only rejected KWs (REJ) are written intoFILMO (separate FILMO). It will be appreciated that in case (ii), forperformance reasons, the address adder in the hardware may sit directlyon the interface port of the CT to the PA/FILMO. Likewise, hardwareimplementations of parameter transformation may also me employed, e.g.,through a lookup table which is loaded before configuration.

8. Re-storing Cache Statistics

International Patent WO 99/44120 (PACT10) describesapplication-dependent cache statistics and control. This method permitsan additional data-dependent optimization of cache performance becausethe data-dependent program performance is expressed directly in cacheoptimization.

One disadvantage of the known method is that cache performance isoptimized only during run time. When the application is restarted, thestatistics are lost. When a SubConf is removed from the cache, itsstatistics are also lost and are no longer available, even when calledup again even within the same application processing.

In an example embodiment according to the present invention, ontermination of an application or removal of a SubConf from the cache,the cache statistics may be sent first together with the respective IDto the next higher-level CT by way of the known inter-CT communicationuntil the root CT receives the respective statistics. The statistics maybe stored in a suitable memory, e.g., in a volatile memory, anonvolatile memory or a bulk memory, depending on the application. Thememory may be accessed by way of a host. The statistics may be stored sothat they are allocated to the respective SubConf. The statistics mayalso be loaded again when reloading the SubConf. In a restart ofSubConf, the statistics may also be loaded into the low-level CT.

The compiler may either compile neutral blank statistics or generatesstatistics which seem to be the most suitable statistics for aparticular approach. These statistics preselected by the compiler maythen be optimized in run time according to the approach described here.The preselected statistics may also be stored and made available in theoptimized version the next time the application is called up.

If a SubConf is used by several applications or by different low-levelCTs within one application (or if the SubConf is called up fromdifferent routines), then it may not be appropriate to keep cachestatistics because the request performance and run performance in eachcase may produce different statistics. Depending on the application,either no statistics are used or a SubconfM may be used.

When using a SubConfM, the transfer of parameters may be extended sothat cache statistics are transferred as parameters. If a SubConfM isterminated, the cache statistics may be written back to the SubConf(ORIGIN) which previously called up the SubConfM. In the termination ofORIGIN, the parameters may then be stored together with the cachestatistics of ORIGIN. The statistics may be in a subsequent call-up andagain be transferred as parameters to the SubConfM.

Keeping and storing application-based cache statistics may be also besuitable for microprocessor, DIPS, FPGA and similar modules.

9. Structure of the Configuration Bus System

PACT07 describes an address—and pipeline-based data bus systemstructure. This bus system is suitable for transmitting configurationdata.

In an example embodiment of the present invention, in order to transmitdata and configurations over the same bus system, status signalsindicating the type of data transmitted may be introduced. The bussystem may be designed so that the CT can optionally read backconfiguration registers and data registers from a PAE addressedpreviously by the CT.

Global data as describe in PACT07 as well as KWs may be transmitted overthe bus system. The CT may act as its own bus node. A status signal maybe employed to characterize the transmission mode. For example, thefollowing structure is possible with signals S0 and S1:

S1 S0 Meaning 0 0 Write data 0 1 Read data 1 0 Write a KW and/or a PAEaddress 1 1 Return a KW or any register from the addressed PAE

The REJ signal may be added to the bus protocol (ACK) according toPACT07 to signal rejects to the CT describe in FILMO protocol.

10. Example Procedure for Combining Individual Registers

Independent configuration registers may be used for a logical separationof configuration data. The logical separation may be needed for thedifferential-configuration because logically separated configurationdata is not usually known when carrying out a differentialconfiguration. This may result in a large number of individualconfiguration registers, each individual register containing acomparatively small amount of information. In the following example, the3-bit configuration values KW-A, B, C, D can be written or modifiedindependently of one another:

0000 0000 0000 0 KW-A 0000 0000 0000 0 KW-B 0000 0000 0000 0 KW-C 00000000 0000 0 KW-D

Such a register set may be inefficient, because only a fraction of thebandwdith of the CT bus is used.

The structure of configuration registers may be greatly optimized byassigning an enable to each configuration value, indicating whether thevalue is to be overwritten in the current configuration transfer.

Configuration values KW-A, B, C, D of the above example are combined inone configuration register. An enable is assigned to each value. Forexample, if EN-x is logical “0,” the KW-x is not changed in theinstantaneous transfer; if EN-x is logical “1,” KW-x is overwritten bythe instantaneous transfer.

En-A KW-A En_B KW-B En-C KW-C En-D KW-D11. Wave Reconfiguration (WRC)

PACT13 describes a reconfiguration method (“wave reconfiguration “or”“WRC”) in which reconfiguration is synchronized directly andchronologically with the data stream See, e.g., FIG. 24 in PACT13.

The proper functioning of Wave reconfiguration, may require thatunconfigured PAEs can neither accept nor send data or triggers. Thismeans that an unconfigured PAE behaves completely neutrally. This may beprovided in VPU technology by using handshake signals (e.g., RDY/ACK)for trigger buses and data buses (see, e.g., U.S. Pat. No. 6,425,068).An unconfigured PAE then generates

-   -   no RDYs, so no data or triggers are sent,    -   no ACKs, so no data or triggers are received.

This mode of functioning is not only helpful for wave reconfiguration,but it is also one of the possible bases for run time reconfigurabilityof VPU technology.

An extension of this approach is explained below. Reconfiguration may besynchronized with ongoing data processing. Within data processing in thePA, it is possible to decide

-   I. which next SubConf becomes necessary in the reconfiguration;-   ii. at what time the SubConf must become active, e.g., with which    data packet (ChgPkt) the SubConf must be linked.

The decision as to which configuration is loaded may be made based onconditions and is represented by triggers (wave configurationpreload=WCP).

Linking of the data packets to the KWs of a SubConf may be ensured bythe data bus protocol (RDY/ACK) and the CT bus protocol (CHECK,ACK/REJ). An additional signal (wave configuration trigger=WCT) mayindicate in which data packet (ChgPkt) reconfiguration is to beperformed and optionally which new configuration is to be carried out orloaded. WCT can be implemented through simple additional lines or thetrigger system of the VPU technology. Multiple VPUs may be usedsimultaneously in the PA, and each signal may control a differentreconfiguration.

11.1. Example Procedure for Controlling the Wave Reconfiguration

It will appreciated that a distinction may be made between twoapplication-dependent WRCs:

-   A1) wave reconfiguration within one SubConf,-   A2) wave reconfiguration of different SubConfs.    In terms of the hardware, a distinction may be made between two    basic types of implementation:-   I1) implementation in the CT and execution on request-   I2) implementation through additional configuration registers    (WRCReg) in the PAEs. Example embodiments of the WRCRegs are    described below. The WRCs are either be-   a) preloaded by the CT at the time of the first configuration of the    respective SubConf, or-   b) preloaded by the CT during execution of a SubConf depending on    incoming WCPs.

During data processing, the WRCRegs that are valid at that time may beselected by one or more WCTs.

The effects of wave reconfiguration on the FILMO principle are discussedbelow.

11.1.1. Performing WRC According to A1

Reconfiguration by WRC may be possible at any time within a SubConf(A1). First, the SubConf may be configured normally, so the FILMOprinciple is ensured. During program execution, WRCs may need to useonly resources already allocated for the SubConf.

Case I1)

WRC may performed by differential configuration of the respective PAEs.WCP may be sent to the CT. Depending on the WCP, there may be a jump toa token within the configured SubConf:

An example code is given below:

begin SubConf main: PAE 1, CHECK&GO PAE 2, CHECK&GO . . . PAE n,CHECK&GO set TriggerPort 1 // WCT 1 set TriggerPort 2 // WCT 2scheduler: on TriggerPort 1, do main1 // jump depending on WCT onTriggerPort 2, do main2 // jump depending on WCT wait: wait for triggermain1: PAE 1, DIFFERENTIAL&GO PAE 2, DIFFERENTIAL&GO . . . PAE n,DIFFERENTIAL&GO wait for trigger main2: PAE 1, DIFFERENTIAL&GO PAE 2,DIFFERENTIAL&GO . . . PAE n, DIFFERENTIAL&GO wait for trigger endSubConf

The interface (TrgIO) between CT and WCP may be configured by “setTriggerport.” According to the FILMO protocol, TrgIO behaves like a PAEwith respect to the CT, e.g., TrgIO corresponds exactly to the CHECK,DIFFERENTIAL, GO protocol and responds with ACK or REJ for each triggerindividually or for the group as a whole.

If a certain trigger has already been configured, it may Despond withREJ.

If the trigger is ready for configuration, it responds with ACK.

FIG. 8 from PACT10 is to be extended accordingly by including thisprotocol.

Upon receipt of WCT, the respective PAE may start the correspondingconfiguration.

Case I2)

If the WRCRegs have already been written during the configuration, theWCP may be omitted because the complete SubConf has already been loadedinto the respective PAE

Alternatively, depending on certain WCPs, certain WRCs may be loaded bythe CT into different WRCRegs defined in the WRC. This may be necessarywhen, starting from one SubConf, it branches off into more differentWRCs due to WRTs than are present as physical WRCRegs.

The trigger ports within the PAEs may be configured so that certainWRCRegs are selected due to certain incoming WRTs:

begin SubConf main: PAE1_TriggerPort 1 PAE1_TriggerPort 2 PAE1_WRCReg1PAE1_WRCReg2 PAE1_BASE, CHECK&GO . . . PAE2_TriggerPort 1PAE2_TriggerPort 2 PAE2_WRCReg1 PAE2_WRCReg2 PAE2_BASE, CHECK&GO . . .PAEn_TriggerPort 1 PAEn_TriggerPort 2 PAEn_WRCReg1 PAEn_WRCReg2PAEn_BASE, CHECK&GO endSubConf11.1.2. Performing WRC According to A2Case I1)

The CT performing a WRC between different SubConfs corresponds inprinciple to A1/I1. The trigger ports and the CT-internal sequencing mayneed to correspond to the FILMO principle. KWs rejected by the PAEs(REJ) may be written to FILMO. These principles have been described inPACT10.

All WCPs may be executed by the CT. It will be appreciated that this mayguarantee a deadlock-free (re)configuration. Likewise, the time ofreconfiguration, which may be marked by WCT, may be sent to the CT andmay be handled atomically by the CT. For example, all PAEs affected bythe reconfiguration may receive the reconfiguration request through WCTeither simultaneously or at least without interruption by anotherreconfiguration request. It will be appreciated that this approach mayguarantee freedom from deadlock.

Case I2)

If the WRCRegs are already written during the configuration the WCP maybe omitted because the complete SubConf is already loaded into therespective PAE.

Alternatively, depending on certain WCPs, WRCs determined by the CT maybe loaded into different WRCRegs defined in the WRC. It will beappreciated this approach may be necessary when, starting from aSubConf, branching off into more different WRCs due to WRTs than thereare physical WRCRegs.

Several WCTs being sent to different PAEs at different times may need tobe prevented because this may result in deadlock.

For example: WCT1 of a SubConf SA reaches PAE p1 in cycle t1, and WCT2of a SubConf SB reaches PAE p2 at the same time. The PAEs are configuredaccordingly. At time t2, WCT1 reaches p2 and. WCT2 reaches p1. Adeadlock has occurred. It should also be pointed out that this examplecan also be applied in principle to A2-I1. It will be appreciated that,this is why WCT there may be sent through the trigger port of the CT andmay be handled by the CT.

A deadlock may also be prevented by the fact that the WCTs generated bydifferent PAEs (sources) are prioritized by a central instance (ARB).This permits exactly one WCT is sent to the respective PAEs in onecycle. Various approaches to prioritization may be used. Exampleprioritization approaches are listed below.

-   a) An arbiter may be used. For example, the round robin arbiter    described in PACT10 is especially suitable. It will be appreciated    that the exact chronological order of occurrence of WCTs may be    lost.-   b) If chronological order is to be preserved, the following example    methods are suggested:    -   b1) A FIFO first stores the incoming WCTs in order of receipt.        WCTs received simultaneously are stored together. If no WCT        occurs at a given time, no entry is generated. An arbiter        downstream from the FIFO selects one of the entries if there        have been several at the same time.    -   b2) A method described in PACT18 permits time sorting of events        on the basis of an associated time information (time stamp). The        correct chronological order of WCTs may be ensured by analyzing        this time stamp.

Suitable relaying of WCTs from ARB to the respective PAEs may ensurethat prioritized WCTs are received by the PAEs in the correct order. Anexample approach to ensuring this order is for all triggers going fromARB to the respective PAEs to have exactly the same length and transittime. This may be ensured by suitable programming. This may also beensured by a suitable layout through a router, e.g., by adjusting thewiring using registers to compensate for latency at the correspondingpoints. To ensure correct relaying, the procedure described in PACT18may also be used for time synchronization of information.

No explicit prioritization of WCPs may be needed because the WCPs sentto the CT may be processed properly by the FILMO principle within theCT. It may be possible to ensure that the time sequence is maintained,e.g., by using the FILMO principle (see 2.1e).

11.1.3. Note for all Cases

The additional configuration registers of the PAEs for wavereconfiguration may be configured to behave according to the FILMOprinciple, i.e., the registers may support the states described and thesequences implemented and respond to protocols such as CHECK andACK/REJ.

11.2. Example Reconfiguration Protocols and Structure of WRCReq

The wave reconfiguration procedure will now be described in greaterdetail. Three alternative reconfiguration protocols are described below.

Normal CT protocol: The CT may reconfigure each PAE individually onlyafter receipt of a reconfiguration reques. For example, the CT mayreceive a reconfiguration request for each PAE reached by ChgPkt. Thisapproach may not be efficient because it entails a very highcommunication complexity, e.g., for pipelined bus systems.

Synchronized pipeline: This protocol may be much more efficient. Thepipelined CT bus may be used as a buffer. The pipeline register assignedto a PAE may store the KWs of this PAE until the PAE can receive theKWs. Although the CT bus pipeline (CBP) is blocked, it can be filledcompletely with the KWs of the wave reconfiguration.

-   a) If the CBP runs in the same direction as the data pipeline, a few    cycles of latency time may be lost. The loss may occur until a KW of    the PAE which follows directly is received by its pipeline register    after a PAE has received a KW.-   b) If the CBP runs opposite the data pipeline, the CBP can be filled    completely with KWs which are already available at the specific    PAEs. Thus, wave reconfiguration without any time lag may be    possible.

Synchronized shadow register: (This protocol may be the most efficient).Immediately after selection of the SubConf (I) and before receipt ofChgPkt (ii), the CT may write new KWs into the shadow registers of allPAEs. The shadow registers may be implemented in any embodiment. Thefollowing possibilities are suggested in particular: a) a register stageconnected upstream from the actual configuration register, b) a parallelregister set which is selected by multiplexers, c) a FIFO stage upstreamfrom the actual configuration registers. At the time when ChgPkt (ii) isreceived by a PAE, it copies the shadow register into the correspondingconfiguration register. In the optimum case, this copying may take placein such a way that no working cycle is lost. If no writing into theshadow register takes place (e.g., if it is empty) despite the receiptof ChgPkt, data processing may stop until the KW is received by theshadow register. If necessary, the reconfiguration request may berelayed together with ChgPkt from one PAE to the next within a pipeline.

12. Forms of Parallelism and Sequential Processing

Due to a sufficiently high reconfiguration performance, sequentialcomputational models can be mapped in arrays. Pro example, the low-levelCTs may represent a conventional code fetcher. The array may operatewith microprogrammable networking as a VLIW-ALU. Different forms ofparallelism may be mapped in arrays of computing elements. Examples mayinclude:

-   Pipelining: Pipelines may be made up of series-connected PAEs.    VPU-like protocols may allow simple control of the pipeline.-   Instruction level parallelism: Parallel data paths may be    constructed through parallel-connected PAEs. VPU-like protocols,    e.g., the trigger signals, allow a simple control.-   SMP, multitasking and multiuser: Independent tasks may be executed    automatically in parallel in one PA. It will be appreciated that    this parallel execution may be facilitated by the freedom from    deadlock of the configuration methods.

With a sufficient number of PAEs, all the essential parts ofconventional microprocessors may be configured on the PA. This may allowsequential processing of a task even without a CT. The CT need notbecome active again until the configured processor is to have adifferent functionality, e.g., in the ALU, or is to be replacedcompletely.

13. Exemplary Embodiments and Diagrams

FIGS. 1 through 3 show the structure of an example SubConf. CW-PAEindicates the number of a KW within a PAE having the address PAE (e.g.,2-3 is the second KW for the PAE having address 3). In addition, thisalso shows the flags C=check, D=differential, G=go), a set flag beingindicated with “*” symbol.

FIG. 1 illustrates the simplest linear structure of a SubConf. Thisstructure has been described in PACT10. A PAE may be tested during thefirst configuration (C), then may be configured further (D) and finallyis started (G) (see PAE having address 0). Simultaneous testing andstarting are also possible (CG,) This is illustrated for the PAE havingaddress 1 (0101).

FIG. 2 illustrates a SubConf which has been re-sorted so that a barrier(0201) has been introduced. All PAEs must be tested before the barrier.The barrier then waits until receipt of all ACKs or REJs. If no REJoccurs, the barrier is skipped, the differential configurations areperformed, and the PAEs are started. If a REJ occurs, the barrier is notskipped, and instead FILMO runs are executed until no more REJ occursand then the barrier is skipped. Before the barrier, each PAE must betested, and only thereafter can the PAEs be configured differentiallyand started. If testing and starting originally took place in the samecycle, the KW must now be separated (0101

0202, 0203).

FIG. 3 illustrates an example a SubConf that has been re-sorted so thatno barrier is necessary. Instead a latency period during which nofurther check can be performed is inserted between check and receipt ofACK/REJ. This may be accomplished by combining the KWs into atoms(0301). The first KW of an atom may perform a check (0302). The blockmay then be filled with differential KWs or optionally NOPs (0303) untilthe end of the latency period. The number of differential KWs depends onthe latency period. For reasons of illustration, a latency period ofthree cycles has been selected as an example. ACK/REJ is received at0304. At this point a decision may be made as to whether configurationis to be continued with the next Kw, which may (but need notnecessarily) contain a check (0305). Alternatively, the configurationmay be terminated on the basis of a REJ to preserve the order.

It will be appreciated that in configuring a PAE X a check may first beperformed then, receipt of ACK/REJ may be waited on. A PAE that hasalready been checked may be configured further during this period oftime, or NOPs must be introduced. PAE X may then be configured further.Example: Check of PAE (0302), continuation of configuration (0306). At0307, NOPs may need to be introduced after a check because nodifferential configurations are available. Points 0308 illustrate thesplitting of configurations over multiple blocks (three in this case),with one check being omitted (0309).

FIG. 4 illustrates an example state machine for implementation of PAEstates, according to an example embodiment of the present invention. Theinitial status is IDLE (0401). By configuring the check flag (0405), thestate machine goes into the “allocated” state (0402). Configuring theLAST flag (0409, 0408) starts the PAE; the status is “configured”(0404). By local reset (0407) the PAE goes into the “unconfigured” state(0403). In this embodiment, the PAE returns to IDLE only after a queryabout its status by LOCK/FREE (0406).

Local reset and LAST can also be sent by the CT through a broadcast (seemoduleID).

FIGS. 5 through 9 show possible implementations of FILMO procedures, asdescribed in section 5. It will be appreciated that only the relevantsubassemblies which function as an interface with the PA are shown.Interfaces with the CT are not described here. These can be implementedas described in PACT10, with minor modifications, if any.

FIG. 5 illustrates the structure of a CT interface to the PA when usinga STATELUT, according to an example embodiment of the present invention.According to 5.1. A CT 0501 having RAM and integrated FILMO (0502) isshown in abstracted form and is not the function of the CT is describedin PACT10 and PACT05. The CT may inquire as to the status of the PA(0503) by setting the LOCK signal (0504). Each PAE whose status haschanged since the last LOCK relays (0506) this change to the STATELUT(0505). This relaying may take place so that the STATELUT can allocateits status uniquely to each PAE. Several conventional approaches may beused for this purpose. For example, each PAE may send its address andstatus to the STATELUT, which then stores the status of each PAE underits address.

The CT may write KWs (0510) first into a register (0507). At the sametime, a lookup may performed under the address (#) of the PAE pertainingto the respective KW in the STATELUT (0505). If the status of the PAE is“not configured,” the CT may receive an ACK (0509), otherwise a REJ. Asimple protocol converter (0508) converts an ACK into a RDY in order towrite the KW to the PA, and REJ is converted to notRDY to preventwriting to the PA.

It will be appreciated that relaying LOCK, RDY and KW to the PA and inthe PA, like the acknowledgment of the status of the PAEs by the PA, maybe pipelined, e.g., by running through registers.

FIG. 6 illustrates an example procedure for re-sorting KWs, according toan embodiment of the present invention. This procedure has a relativelylow level of complexity. A CT (0601) having integrated FILMO (0602) ismodified so that an acknowledgment (0605) (ACK/REJ) is expected only forthe first KW (0604) of an atom sent to the PA (0603). The acknowledgmentmay be analyzed for the last KW of an atom. In the case of ACK, theconfiguration may be continued with the next atom, and REJ causestermination of configuration of the SubConf.

FIG. 7 illustrates an example FILMO (0701), according to an exampleembodiment of the present invention. The RELJMP memory (0702) may beassigned to FILMO, each entry in RELJMP being assigned to a FILMO entry.FILMO here is designed as an integrated FILMO, as described in PACT10.It will be appreciated that RELJMP may represent a concatenated list ofKWs to be configured. It will also be appreciated that FILMO may containCT commands and concatenation, as described in PACT10. The concatenatedlist in RELJMP may be generated as follows: The read pointer (0703)points to the KW which is being configured. The address of the KWrejected (REJ) most recently is stored in 0704. If the KW (0706) beingconfigured is accepted by the PA (0707) (ACK, 0708), then the valuestored in 0702 at the address to which 0703 points may be added to 0703.This results in a relative jump.

The KW being configured at the moment may be rejected (REJ, 0708. Then,the difference between 0703 and 0704, may be calculated by a subtractor(0705. The difference may be stored in RelJmp, e.g., at the address ofthe KW rejected last and stored in 0704. The current value of 0703 maybe stored in 0704. Then the value stored in 0702 at the address to which0703 points may be added to 0703. This yields a relative jump. Controlmay be assumed by a state machine (0709). The state machine may beimplemented according to the sequence described here. The address forRelJmp may be determined by the state machine 0709, e.g., using amultiplexer (0710). Depending on the operation, the address may beselected from 0703 or 0704. To address 0701 and 0702 efficiently anddifferently at the same time, 0702 may be physically separated from0701, so that there are two separate memories which can be addressedseparately.

0711 illustrates the functioning of the relative addressing. The addresspointing at an entry in RelJmp may be added to the content of RelJmp,yielding the address of the next entry.

FIG. 8 illustrates an example procedure for analyzing acknowledgments,possible implementation of the method according to an example embodimentof the present invention Entries in FILMO (O801) may be managedlinearly, so RelJmp may not be needed. FILMO 0801 is implemented as aseparate FILMO. KWs (0803) written into the PA (0802) may be addressedby a read pointer (0804). All KWs may be written in the order of theirconfiguration into a FIFO or a FIFO-like memory (0805).

The FIFO may be implemented as a shift register. The depth of the memoryis exactly equal to the number of cycles elapsing from sending a KW tothe PA until receipt of the acknowledgment (RDY/ACK, 0806).

-   -   Upon receipt of a REJ, the rejected KW, which is assigned to the        REJ and is at the output of the FIFO, may be written into 0801.        REJ is used here as a write signal for FILMO (REJ->WR). The        write address may be generated by a write pointer (0807), which        may be incremented after the write access.    -   Upon receipt of an ACK, nothing happens, the configured KW        assigned to the ACK is ignored and 0807 remains unchanged.

It will be appreciated that this procedure may result in a new linearsequence of rejected KWs in the FILMO. The FILMO may be implemented as adual-ported RAM with separate read and write ports.

FIG. 9 illustrated an example procedure for pre-fetching, according toan example embodiment of the present invention. It will be appreciatedthat this procedure is a modification of the procedure described in 5.3.

The KW (0902) to be written into the PA (0901) may be addressed by aread pointer (0909) in FILMO (0910). The address and flags (0902 a) ofthe PAE to be configured may be sent to the PA as a test. The KW havingthe address of the PAE to be configured may be written to a FIFO-likememory (0903). It will be appreciated that this FIFO may correspond to0805. 0902 a may be transmitted to the PA in a pipeline. Access isanalyzed and acknowledged in the PAE addressed. Acknowledgment (RDY/ACK)may also be sent back pipelined (0904). 0903 delays exactly for as manycycles as have elapsed from sending 0902 a to the PA until receipt ofthe acknowledgment (RDY/ACK, 0904).

-   -   If acknowledged with ACK, the complete KW (0905) (address+data)        at the output of 0903 which is assigned to the respective        acknowledgment may be pipelined to the PA (0906). No        acknowledgment is expected for this, because it is already known        that the addressed PAE will accept the KW.    -   In the case of REJ, the KW may be written back into the FILMO        (0907). A write pointer (0708) which corresponds to 0807, may be        used for this purpose. The pointer may be incremented in this        process.

0904 may be converted here by a simple protocol converter (0911) (i)into a write signal for the PA (RDY) in the case of ACK and (ii) into awrite signal 0901 for the FILMO (WR) in the case of REJ.

It will be appreciated that a new linear sequence of rejected KWs may bestored in the FILMO. The FILMO may be implemented as a dual-ported RAMwith separate read and write ports.

FIG. 10 illustrates an example inter-CT protocol, according to anexample embodiment of the present invention. Four levels of CT areshown: the root CT (1001), CTs of two intermediate levels (1002 a-b and1003 a-d), the low-level CTs (1004 a-h) and their FILMOs (1005 a-h). Inthe PA assigned to 1004 e, a trigger may be generated. The trigger cannot be translated to any local SubConf within 1004 e. Instead, thetrigger may be assigned to an EnhSubConf. CT 1004 e may send a REQUESTfor this EnhSubConf to CT 1003 c. CT 1003 c has not cached the ID chain.EnhSubConf is partially also carried out on CT 1004 g, which is not aleaf of CT 1003 c. Thus, CT 1003 c may relay the REQUEST to CT 1002 b.The hatching indicates that CT 1002 b might have cached the ID chainbecause CT 1004 g is a leaf of CT 1002 b. However, CT 1002 b has neitheraccepted nor cached the ID chain and therefore may request it from CT1001. CT 1001 may load the ID chain from the CTR, as described in seePACT10. CT 1001 may send the ID chain to CT 1002 b. This process isreferred to below as GRANT. CT 1002 b has cached the ID chain becauseall participating CTs are leaves of CT 1002 b.

Then CT 1002b may send GRANT to CT 1003c and CT 1003d as an atom, e.g.,without interruption by another GRANT. The ID chain may be split hereand sent to two different CTs, so none of the receivers may be a commonarbiter of all leaves. The SPLIT flag may be set; the receivers and alllower-level CTs can no longer cache the ID chain. CT 1003c and CT 1003dagain send GRANT to low-level CTs 1004f and 1004g as an atom. Thelow-level CTs store the incoming GRANT directly in a suitable list,indicating the order of SubConf to be configured. This list may bedesigned to be separate, or it may be formed by performing theconfiguration directly by optionally entering the rejected KWs intoFILMO.

Two example variants for the low-level CTs:

-   -   They have already cached the SubConf to be started,        corresponding to the ID according to the ID chain. Here, the        configuration is started immediately,    -   They have not yet cached the SubConf corresponding to the ID        according to the ID chain. Here, they may need to request it        first from the higher-level CTs. The request (GET) is        illustrated in FIG. 11, where it is again assumed that none of        the CTs from the intermediate level has cached the SubConf.        Therefore, the respective SubConf may be loaded by the root CT        from the CTR and Bent to the low-level CTs (DOWNLOAD). Thia        sequence is described in more detail in PACT10.

After receipt of a GRANT, the received GRANT may need to be executedbefore any other GRANT. For example, if GRANT A is received before GRANTB, then GRANT A may need to be 30 configured before GRANT B. This mayalso be needed if the SubConf of GRANT A needs to be loaded first whilethe SubConf of GRANT B would be cached in the low-level CT and could bestarted immediately. The order of incoming GRANTs may need to bemaintained, because otherwise a deadlock can occur among the EnhSubConf.

In an alternative embodiment of the procedure described here,

CTs of the CTTREE may directly access configurations without includingthe higher-level CTs. The CTs may have a connection to any type ofvolatile memory, nonvolatile memory or bulk memory. For example, thismemory may be an SRAM, DRAM, ROM, flash, CDROM, hard drive or serversystem, which may be connected via a network (WAN, LAN, Internet). Itwill be appreciated that a CT may directly access a memory forconfiguration data, bypassing the higher-level CTs. In such a case, theconfiguration may be synchronized within the CTTREE, includinghigher-level CTs, e.g., with EnhSubConf.

FIG. 12 illustrates three examples (FIGS. 12 a-12 c), a configurationstack of 8 CTs (1201-1208), according to an example embodiment of thepresent invention. The configuration stack contains the list of SubConfsto be configured. The SubConfs may be configured in the same order asthey are entered in the list. For example, a configuration stack may beformed by concatenation of individual SubConfs as described in PACT10(FIGS. 26 through 28). Another alternative is a simple list of IDspointing to SubConfs, as shown FIG. 12. Lower-level entries may beconfigured first, and higher-level entries may be configured last. FIG.12 a illustrates two EnhSubConfs (1210, 1211) which are positionedcorrectly within the configuration stack of the individual CTs. Theindividual SubConfs of the EnhSubConfs are configured in the properorder without a deadlock. The order of GRANTs was preserved. The examplein FIG. 12 b is also correct. Three EnhSubConf are shown (1220, 1221,1222). 1220 is a large EnhSubConf affecting all CTs. 1221 pertains onlyto CTs 1202-1206, and another pertains only to CTs 1207 and 1208. AllSubConfs are configured in the proper order without a deadlock. TheGRANT for 1222 was processed completely before the GRANT for 1220, andthe latter was processed before the GRANT for 1221.

The example in FIG. 12 c illustrates several deadlock situations. In1208, the order of GRANTs from 1230 and 1232 has been reversed,resulting in resources for 1230 being occupied in the PA allocated to1208 and resources for 1232 being occupied in the PA allocated to 1208.These resources are always allocated in a fixed manner. This results ina deadlock, because no EnhSubConf can be executed or configured to theend.

Likewise, GRANTs of 1230 and 1231 are also chronologically reversed inCTs 1204 and 1205. This also may result in a deadlock for the samereasons.

FIG. 13 a illustrates a performance-optimized version of inter-CTcommunication according to an example embodiment of the presentinvention. A download may be performed directly to the low-level CT.Here, mid-level CTs need not first receive, store and then relay theSubConfs. Instead, these CTs may “listen” (1301, 1302, 1303, LISTENER)and cache the SubConfs. An example schematic bus design is illustratedin FIG. 13 b, according to an example embodiment of the presentinvention. A bypass (1304, 1305, 1306), may carry the download past themid-level CTs. This bypass may be provided as a register.

FIG. 14 illustrates an example circuit providing simple configuration ofSubConf macros, according to an example embodiment of the presentinvention. The example circuit may be provided between a CT and a PA. AKW may be transmitted by the CT over the bus (1401). The KW is brokendown into its configuration data (1402) plus PAE addresses X (1403) andY (1404). It will be appreciated that, in the case of multidimensionaladdressing, more addresses may be broken down. 1405 adds an X offset tothe X address, and 1406 adds a Y offset to the Y address. The offsetsmay be different and may be stored in a register (1407). Theparameterizable part of the data (1408) may be sent as an address to alookup table (1409) where the actual values are stored. The values maybe linked (1410) to the nonparameterizable data (1412). A multiplexer(1413) may be used to select whether a lookup is to be performed orwhether the data should be used directly without lookup. The choice maybe made using a bit (1411). All addresses and the data may be linkedagain and sent on a bus to the PA. Depending on implementation, theFILMO may be connected upstream or downstream from the circuit describedhere. Integrated FILMOs may be connected upstream, and separate FILMOsmay be connected downstream. The CT may set the address offsets and theparameter translation in 1409 via bus 1415. 1409 may be implemented as adual-ported RAM.

A corresponding KW may be structured as follows:

X address Y address Data Address for MUX = 1 1409 X address Y addressData Data MUX = 0

If MUX=1, then a lookup may be performed in 1409. If MUX=0, data may berelayed directly to 1414.

FIG. 15 illustrates the execution of an example graph, according to anexample embodiment of the present invention.

The next possible nodes (1 . . . 13) of the graph may be preloaded(prefetch), and preceding nodes and unused jumps may be deleted(delete). Within a loop, the nodes of the loop are not deleted (10, 11,12), and corresponding nodes are removed only after termination. Nodesmay be loaded only if they are not already present in the memory of theCT. Therefore, multiple processing of 11 need not result in multipleloading of 12 or 10; e.g., “delete 8, 9” is ignored in 11 if 8 and/or 9has already been removed.

FIG. 16 illustrates multiple instantiation of an example SubConf macro(1601), according to an example embodiment of the present invention.Various SubConfs (1602, 1603, 1604) call up 1601. Parameters for 1601may be preloaded (1610) in a lookup table (1605) by the requestingSubConf. 1605 is implemented only once but is shown several times inFIG. 16 to represent the various contents.

1601 may be called up. The KWs may be transmitted to 1605, 1606 and1607. These elements operate as follows: Based on a lookup, thecorresponding content of 1605 is linked again (1606) to the KWs. The KWis sent to the PA (1608) after the multiplexer 1413 (1607) selectswhether the original KW is valid or whether a lookup has been performed.

FIG. 17 shows the sequence of an example wave reconfiguration, accordingto an example embodiment of the present invention. Areas shown withsimple hatching represent data-processing PAEs, with 1701 representingPAEs after reconfiguration and 1703 representing PAEs beforereconfiguration. Areas shown with crosshatching (1702) indicate PAEswhich are in the process of being reconfigured or are waiting forreconfiguration.

FIG. 17 a shows the influence of wave reconfiguration on a simplesequential algorithm, according to an example embodiment of the presentinvention. Exactly those PAEs to which a new function has been allocatedmaybe reconfigured. Since a PAE can receive a new function in eachcycle, this may be performed efficiently, e.g., simultaneously.

One row of PAEs from the matrix of all PAEs of a VPU is shown as anexample. The states in the cycles after cycle t are shown with a delayof one cycle each.

FIG. 17 b illustrates the time effect of reconfiguration of largeportions of a VPU, according to an example embodiment of the presentinvention. A number of PAEs of one VPU is shown as an example,indicating the states in the cycles after cycle t with a different delayof several cycles each.

Although at first only a small portion of the PAEs is reconfigured or iswaiting for reconfiguration, this area becomes larger over time, untilall the PAEs have been reconfigured. The increase in size of this area(1702) shows that, due to the time delay in reconfiguration, more andmore PAEs are waiting for reconfiguration. This may result in lostcomputing performance.

A broader bus system may be used between the CT (in particular, thememory of the CT) and the PAEs, providing enough lines to reconfigureseveral PAEs at the same time within one cycle.

Not Wave configured trigger W C D X — X X — Wave reconfiguration X — X —X REJ — X X X — REJ — X X — X Differential wave reconfiguration — Normalconfiguration

FIG. 18 illustrates example configuration strategies for areconfiguration procedure like the “synchronized shadow register”,according to an example embodiment of the present invention. The CT(1801), as well as one of several PAEs (1804), are shown schematicallywith only the configuration registers (1802, 1803) within the PAE and aunit for selecting the active configuration (1805) being illustrated. Tosimplify the drawings, additional functional units within the PAE havenot been shown. Each CT has n SubConfs (1820), the corresponding KWs ofa SubConf being loaded when a WCP occurs (1(n)), in cases-I1, and in thecases-I2, the KWs of m SubConfs from the total number of n are loaded(m(n)). The different tie-ins of WCT (1806) and WCP (1807) are shown, asare the optional WCPs (1808), as described below.

In A1-I1, a next configuration may be selected within the same SubConfsby a first trigger WCP. This configuration may use the same resources,alternative resources may be used that already prereserved and are notoccupied by any other SubConfs except for that optionally generating theWCP. The configuration may be loaded by the CT (1801). In the exampleshown here, the configuration is not executed directly, but instead isloaded into one of several alternative registers (1802). By a secondtrigger WCT, one of the alternative registers is selected at the time ofthe required reconfiguration. This causes the configuration previouslyloaded on the basis of WCP to be executed.

It will be appreciated that a certain configuration may be determinedand preloaded by WCP. The time of the actual change in functioncorresponding to the preloaded reconfiguration may be determined by WCT.

WCP and WCT may each be a vector, so that one of several configurationsmay be preloaded by WCT(v₁). The configuration to be preloaded may bespecified by the source of WCP. Accordingly, WCT(v₂) may select one ofseveral preloaded configurations. In this case, a number ofconfiguration registers 1802 corresponding to the quantity ofconfigurations selectable by v2 may be needed. The number of suchregisters may be fixedly predetermined so that v2 corresponds to themaximum number.

An example version having a register set 1803 with a plurality ofconfiguration registers 1802 is shown in A1-I2. If the number ofregisters in 1803 is large enough that all possible followingconfigurations can be preloaded directly, the WCP can be eliminated. Inthis case, only the time of the change of function as well as the changeitself may need to be specified by WCT(v₂).

A2-I1 illustrates an example WRC where the next configuration does notutilize the same resources or whose resources are not prereserved or areoccupied by another SubConf in addition to that optionally generatingthe WCP(v₁) The freedom from deadlock of the configuration may beguaranteed by the FILMO-compliant response and the configuration onWCP(v₁). The CT also may start configurations by WCT(v₂) (1806) throughFILMO-compliant atomic response to the receipt of triggers (ReconfReq)characterizing a reconfiguration time.

In A2-I2, all the following SubConfs are either preloaded intoconfiguration register 1803 with the first loading of a SubConf.Alternatively, if the number of configuration registers is notsufficient, the following SubConfs may be re-loaded by the CT, e.g., byway of running a WCP(v₁).

The triggers (ReconfReq, 1809) which may determine a reconfigurationtime and trigger the actual reconfiguration may first be isolated intime by way of a suitable prioritizer (1810). The triggers may then besent as WCT(v₂) to the PAEs so that exactly only one WCT(v₂) is alwaysactive on one PAE at a time, and the order of incoming WCT(v₂)s isalways the same with all the PAEs involved.

In the case of A2-I1 and A2-I2, an additional trigger system may beused. In processing of WCT by CT 1801, i.e., in processing by 1810,there may be a considerable delay until relaying to PAE 1804. However,the timing of ChgPkt may need to be rigorously observed becauseotherwise the PAEs may process the following data incorrectly.Therefore, another trigger (1811, WCS=wave configuration stop) may beused. The WCS trigger only stops data processing of PAEs until the newconfiguration has been activated by arrival of the WCT. WCS is may begenerated within the SubConf active at that time. The ReconfReq and WCSmay be identical, because if ReconfReq is generated within the SubConfcurrently active, this signal may indicate that ChgPkt has been reached.

FIG. 19 illustrates an alternative implementation of A1-I2 and A2-I2,according to an example embodiment of the present invention. A FIFOmemory (1901) may be used to manage the KW instead of using a registerset. The order of SubConfs preselected by WCP may be fixed. Due to theoccurrence of WCT (or WCS, alternatively represented by 1902), only thenext configuration can be loaded from FIFO. The function of WCS, e.g.,stopping ongoing data processing, may be exactly the same as thatdescribed in conjunction with FIG. 18.

FIG. 20 illustrates a section of a row of PAEs carrying out areconfiguration method like the “synchronized pipeline” according to anexample embodiment of the present invention. One CT (2001) may beallocated to multiple CT interface subassemblies (2004) of PAEs (2005).2004 may be integrated into 2005 and is shown with an offset only tobetter illustrate the function of WAIT and WCT. It will be appreciatedthat signals for transmission of configuration data from 2004 to 2005are not shown here.

The CT may be linked to PAEs 2004 by a pipelined bus system, 2002representing the pipeline stages. 2002 may include a register (2003 b)for the configuration data (CW) and another register (2003 a) having anintegrated decoder and logic. Register 2003 a may decode the addresstransmitted in CW and sends a RDY signal to 2004 if the respective localPAE is addressed. Register 2003 a may send a RDY signal to the next step2002, if the local PAE is not addressed. Accordingly, 2003 a may receivethe acknowledgment (GNT), from 2002 or 2004, e.g., as a RDY/ACK. Thisresults in a pipelined bus which transmits the CW from the CT to theaddressed PAE and its acknowledgment back to the CT.

When WCT is active at 2004, pending CWs which are characterized withWAVE as part of the description may be configured in 2004. Here, GNT mayacknowledged with ACK. If WCT is not active but CWs are pending forconfiguration, then GNT may not be acknowledged. The pipeline may beblocked until the configuration has been performed.

If 2005 is expecting a wave reconfiguration, characterized by an activeWCT, and no CWs characterized with WAVE are already present at 2004,then 2004 may acknowledge with WAIT. This may put the PAE (2005) in awaiting, non-data-processing status until CWs characterized with WAVEhave been configured in 2004. CWs that have not been transmitted withWAVE may be rejected with REJ during data processing.

It will be appreciated that optimization may be performed by specialembodiments for particular applications. For example, incoming CWscharacterized with WAVE and the associated reconfiguration may be storedtemporarily by a register stage in 2004, preventing blocking of thepipeline if CWs sent by the CT are not accepted immediately by theaddressed 2004. For further illustration, 2010 and 2011 may be used toindicate the direction of data processing. If data processing proceedsin direction 2010, a rapid wave reconfiguration of the PAEs is possibleas follows. The CT may send CWs characterized with WAVE into thepipeline so that first the CWs of the most remote PAE are sent. If CWscannot be configured immediately, the most remote pipeline stage (2002)may be blocked. Then, the CT may send CWs to the PAE which is then themost remote and so forth, until the data is ultimately sent to the nextPAE.

As soon as ChkPkt runs through the PAEs, the new CWs may be configuredin each cycle. It will be appreciated that this approach may also beefficient if ChgPkt is running simultaneously with transmission of CWsfrom the CT through the PAEs. In this case, the respective CW requiredfor configuration may also be pending at the respective PAE in eachcycle.

If data processing proceeds in the opposite direction (2011), thepipeline may optionally be configured from the PAE most remote from theCT to the PAE next to the CT. If ChgPkt does not take placesimultaneously with data transmission of the CWs, the method may remainoptimal. On occurrence of ChgPkt, the CWs may be transmitted immediatelyfrom the pipeline to 2004.

However, if ChgPkt appears simultaneously with CWs of wavereconfiguration, this may result in waiting cycles. For example, PAE Bis to be configured on occurrence of ChgPkt in cycle n. CWs are pendingand are configured in 2004. In cycle n+1, ChgPkt (and thus WCT) arepending at PAE C. However, in the best case, CWs of PAE C aretransmitted only to 2002 of PAE B in this cycle, because in thepreceding cycle, 2002 of PAE B was still occupied with its CW. Only incycle n+2 are the CWs of PAE C in 2002 and can be configured. A waitingcycle has occurred in cycle n+1.

FIG. 21 illustrates a general synchronization strategy for a wavereconfiguration, according to an example embodiment of the presentinvention. A first PAE 2101 may recognize the need for reconfigurationon the basis of a status that is occurring. This recognition may takeplace according to the usual methods, e.g., by comparison of data orstates. Due to this recognition, 2101 sends a request (2103) to one ormore PAEs (2102) to be reconfigured. This may be accomplished through atrigger. This may stop the data processing. In addition, 2101 sends asignal (2105), which may also be the same as signal 2103, to a CT (2104)to request reconfiguration. CT 2104 may reconfiguration 2102 (2106).After successful reconfiguration of all PAEs to be reconfigured, the CTmay inform 2101 (2107) regarding the end of the procedure, e.g., by wayof reconfiguration. Then 2001 may take back stop request 2103, and dataprocessing may be continued. Here, 2108 and 2109 each symbolize data andtrigger inputs and outputs.

FIG. 22 illustrates an example approach for using routing measures toensure a correctly timed relaying of WCT, according to an exampleembodiment of the present invention. Several WCTs may be generated fordifferent PAEs (2201) by a central instance (2203). The WTCs may need tobe coordinated with one another in time. The different distances to PAEs2201 in the matrix may result in different transmit times or latencytimes. Timing coordination may be achieved in the present examplethrough suitable use of pipeline stages (2202). These may be allocatedusing a router assigned to the compiler, as described in PACT13. Theresulting latencies indicated here as d1-d5. It can be seen here thatthe same latencies occur in the direction of data flow (2204) in eachstage (column). For example, 2205 may not be necessary, because thedistance of 2206 from 2003 is very small. However, one 2202 each must beinserted for 2207 and 2208 because of the transit time resulting fromthe longer distance, so 2205 may be needed to equalize the transmittime.

FIG. 23 illustrates an example application of wave reconfiguration,according to an example embodiment of the present invention. This figurealso illustrates optional utilization of PAE resources orreconfiguration time to perform a task, yielding an intelligenttrade-off between cost and performance that can be adjusted by thecompiler or the programmer.

A data stream is to be calculated (2301) in an array (2302) of PAEs(2304-2308). A CT (2303) assigned to the array is responsible for itsreconfiguration. 2304 is responsible for recognition of the end state ofdata processing which makes reconfiguration necessary. This recognitionis signaled to the CT. 2306 marks the beginning and 2309 the end of abranch represented by 2307 a, 2307 b or 2307 ab. PAEs 2308 are not used.The various triggers are represented by 2309.

In FIG. 23 a, one of two branches 2307 a, 2307 b may be selected by 2305and activated by trigger simultaneously with data received from 2306.

In FIG. 23 b, branches 2307 a and 2307 b may not need to be completelypreconfigured, but instead both possible branches should share resources2307 ab by reconfiguration. 2305 also selects the branch necessary fordata processing. Information may now be sent to 2303 and also to 2306 tostop data processing until reconfiguration of 2307 ab has been completedaccording to FIG. 21.

FIG. 24 illustrates an example implementation according to of a statemachine for sequence control of the PAE, according to an exampleembodiment of the present invention. The following states may beimplemented:

-   Not Configured (2401)-   Allocated (2402)-   Wait for lock (2403)-   Configured (2404)

The following signals trigger may trigger a change of status:

-   LOCK/FREE (2404, 2408)-   CHECK (2405, 2407)-   RECONFIG (2406, 2409)    -   GO (2410, 2411)

FIG. 25 illustrates an example high-level language compiler, accordingto an example embodiment of the present invention. This compiler hasalso been described in PACT13. The compiler may translate ordinarysequential high-level languages (C, Pascal, Java) to a VPU system.Sequential code (2511) may be separated from parallel code (2508) sothat 2508 is processed directly in the array of PAEs.

There are three possible embodiments for 2511:

-   1. Within a sequencer of a PAE. (See PACT13, 2910)-   2. By using a sequencer configured into the VPU. The compiler    generates a sequencer optimized for the task, while directly    generating the algorithm-specific sequencer code See PACT13, 2801.-   3. On an ordinary external processor. (See PACT13, 3103)-   4. By rapid configuration by a CT. Here the ratio between the number    of PAEs within a PAC and the number of PACs may be selected so that    one or more PACs can be set up as dedicated sequencers. The    dedicated sequencer's op codes and command execution may be    configured by the respective CT in each operating step. The    respective CT may respond to the status of the sequencer to    determine the following program sequence. The status may be    transmitted by the trigger system. The possibility that is selected    may depend on the architecture of the VPU, the computer system and    the algorithm.

This principle was described generally PACT13. However, the exampleembodiment of the present invention may include extensions of the routerand placer (2505).

The code (2501) may first be separated in a preprocessor (2502) intodata flow code (2516) and ordinary sequential code (2517). The data flowcode may be written in a special version of the respective programminglanguage optimized for data flow. 2517 may be tested for parallelizablesubalgorithms (2503) and the sequential subalgorithms may be sorted out(2518). Parallelizable subalgorithms may be placed and routed as macroson a provisional basis.

In an iterative procedure, the macros may be placed, routed andpartitioned (2505) together with the data flow-optimized code (2513).Statistics (2506) evaluate the individual macros as well as theirpartitioning with regard to efficiency, with the reconfiguration time,and the complexity of the reconfiguration. Inefficient macros may beremoved and sorted out as sequential code (2514).

The remaining parallel code (2515) may be compiled and assembled (2507)together with 2516. VPU object code may be output (2508). Statisticsregarding the efficiency of the code generated as well as individualmacros (including those removed with 2514) may be output (2509). It willbe appreciated that the programmer thus receives important informationregarding optimization of the speed of the program.

Each macro of the remaining sequential code may be tested for itscomplexity and requirements (2520). The suitable sequencer in each casemay be selected from a database, which depends on the VPU architectureand the computer system (2519). The selected sequencer may output as VPUcode (2521). A compiler (2521) may generate the assembler code of therespective macro for the respective sequencer selected by 2520. Theassembler code may then be output (2511). 2510 and 2520 are closelylinked together. Processing may proceed iteratively to find the mostsuitable sequencer having the fastest and minimal assembler code.

A linker (2522) may compile the assembler codes (2508, 2511, 2521) andgenerate executable object code (2523).

Definition of Terms

EXAMPLE

-   ACK/REJ: Acknowledgment protocol of a PAE to a (re)configuration    attempt. ACK may indicate that the configuration has been accepted,    REJ may indicate that the configuration has been rejected. The    protocol may provide for waiting for receipt of either ACK or REJ    and optionally inserting waiting cycles until the receipt.-   CT: Unit for interactive configuration and reconfiguration of    configurable elements. A CT may have a memory for temporary storage    and/or caching of SubConfs. CTs that are not root CTs may also have    a direct connection to a memory for SubConfs, which may not need to    be loaded by a higher-level CT.-   CTTREE: One-dimensional or multidimensional tree of CTs.-   EnhSubConf: Configuration containing multiple SubConfs to be    executed on different PACs.-   Configuration: An executable algorithm

Configurable element: An element whose function may be determined by aconfiguration from a range of possible function. For example, aconfigurable element may be designed as a logical function unit,arithmetic function unit, memory, peripheral interface or bus system;this includes in particular elements of known technologies such as FPGA(e.g., CLBs), DPGAs, VPUs and other elements known under the term“reconfigurable computing.” A configurable element may also be a complexcombination of multiple different function units, e.g., an arithmeticunit with an integrated allocated bus system.

-   KW: Configuration word. One or more pieces of data intended for the    configuration or part of a configuration of a configurable element.-   Latency: Delay within a data transmission, which usually takes place    in synchronous systems based on cycles. Latency may be measured in    clock cycles.-   PA: Processing array. This may include an arrangement of multiple    PAEs, including PAEs of different designs.-   PAC: A PA with an associated CT responsible for configuration and    reconfiguration of the PA.-   PAE: Processing array element, configurable element.-   ReconfReq: Triggers based on a status which may require a    reconfiguration.-   Reconfiguration may include loading a new configuration. This    loading may occur simultaneously or overlapping or in parallel with    data processing, without interfering with or corrupting the ongoing    data processing.-   Root CT: Highest CT in the CTTREE. The Root CT may have a connection    to the configuration memory. It may be the only CT so connected.-   SubConf: Part of a configuration composed of multiple KWs.-   WCT: The WCT may indicate the time at which a reconfiguration is to    take place. A WCT may optionally select one of several possible    configurations via transmission of additional information. A WCT may    run in exact synchronization with the termination of the data    processing underway, which may be terminated for the    reconfiguration. If WCT is transmitted later for reasons of    implementation, WCS may be used for synchronization of data    processing.-   WCP: A request for one or more alternative next configuration(s)    from the CT for (re)configuration.-   WCS: Stops the data processing until receipt of WCT. May need to be    used if WCT does not indicate the exact time of a required    reconfiguration.-   Cell: Configurable element

REFERENCES

-   PACT01 4416881-   PACT02 19781412.3 and U.S. Pat. No. 6,425,068-   PACT04 19654842.2-53-   PACT05 19654593.5-53-   PACT07 19880128.9-   PACT08 19880129.7-   PAC10 19980312.9 and 19980309.9 and PCT/DE99/00504-   PACT13 PCT/DE00/01869-   PACT18 10110530.4

1. A method of controlling a data processing system having a cellularstructure, comprising: transmitting a first configuration word to afirst processing unit in the cellular structure; processing data withthe first processing unit in accordance with the first configurationword; transmitting a second configuration word to the first processingunit; transmitting a reconfiguration signal to the first unit, thereconfiguration signal indicating that the first unit should beginprocessing data in accordance with the second configuration word; if thefirst processing unit has completed processing data in accordance withthe first configuration word prior to when the reconfiguration signal isreceived by the first processing unit, processing data with the firstprocessing unit in accordance with the second configuration word; and ifthe first processing unit has not completed processing data inaccordance with the first configuration word, continuing to process datawith the first processing unit in accordance with the firstconfiguration word.
 2. The method of claim 1, further comprising: if thefirst processing unit has completed processing data in accordance withthe first configuration word prior to when the reconfiguration signal isreceived by the first processing unit, sending an acknowledgment signalin response to the receipt of the reconfiguration signal.
 3. The methodof claim 1, further comprising: if the first processing unit has notcompleted processing data in accordance with the first configurationword, sending a rejection signal in response to the receipt of thereconfiguration signal.
 4. The method of claim 1, wherein thereconfiguration signal is transmitted together with the secondconfiguration word.
 5. The method of claim 1, further comprising:storing the second reconfiguration word in the first processing unitprior to the processing of data with the first processing unit inaccordance with the first configuration word, wherein thereconfiguration signal is transmitted after the processing of data withthe first processing unit in accordance with the first configurationword has commenced.
 6. The method of claim 1, further comprising:setting a state variable associated with the first processing unit toindicate the first processing unit is in a configured state prior toprocessing data with the first processing unit in accordance with thefirst configuration word.
 7. The method of claim 6, further comprising:setting the state variable associated with the first processing unit toindicate the first processing unit is in an unconfigured state whenprocessing of data with the first processing unit in accordance with thefirst configuration word has been completed.
 8. The method of claim 7,further comprising: testing the state variable associated with the firstprocessing unit when the reconfiguration signal is received by the firstprocessing unit.
 9. The method of claim 1, further comprising:transmitting a differential reconfiguration signal to the firstprocessing unit.
 10. The method of claim 9, further comprising: if thefirst processing unit is processing data in accordance with the firstconfiguration word when the differential reconfiguration signal isreceived, terminating the processing of data by the first processingunit in accordance with the first configuration word and commencingprocessing of data by the first processing unit in accordance with thesecond configuration word.
 11. The method according to claim 10, furthercomprising: sending an acknowledgment signal from the first processingunit if the first processing unit is processing data in accordance withthe first configuration word when the differential reconfigurationsignal is received by the first processing unit.
 12. The methodaccording to claim 9, further comprising: sending a rejection signalfrom the first processing unit if the first processing unit is notprocessing data in accordance a configuration word when the differentialreconfiguration signal is received by the first processing unit.
 13. Themethod of claim 1, further comprising: delaying the transmission of theconfiguration signal, the delay being sufficient to prevent the secondconfiguration signal from arriving at the first processing unit beforethe first processing unit has completed processing data in accordancewith the first configuration word.
 14. The method of claim 1, furthercomprising: routing the transmission of the reconfiguration signal tothe first processing unit via a first transmission path to the firstprocessing unit that is longer than a shortest transmission path to thefirst processing unit, the first transmission path being selected sothat the first transmission path is sufficiently long to ensure that thereconfiguration signal reaches the first processing unit after theprocessing of data by the first processing unit in accordance with thefirst configuration word has been completed.
 15. The method according toclaim 1, further comprising: sending a start signal to the firstprocessing unit; beginning the processing of data in the firstprocessing unit in accordance with the first configuration word when thestart signal is received by the first processing unit.
 16. A method ofcontrolling a data processing system having a cellular structure,comprising: transmitting a first configuration word to a firstprocessing unit in the cellular structure; setting a state variableassociated with the first processing unit to a value indicative that thefirst processing unit is in a configured state; processing data with thefirst processing unit in accordance with the first configuration word;when the processing of data with the first processing unit in accordancewith the first configuration word has been completed, setting the statevariable associated with the first processing unit to a value indicativethat the first processing unit is in an unconfigured state; transmittinga second configuration word to the first processing unit; transmitting areconfiguration signal to the first unit, the reconfiguration signalindicating that the first unit should begin processing data inaccordance with the second configuration word; if the state variableindicates the first processing unit is in an unconfigured state when thereconfiguration signal is received by the first processing unit,processing data with the first processing unit in accordance with thesecond configuration word; and if the first processing unit is in aconfigured state when the reconfiguration signal is received by thefirst processing unit, continuing to process data with the firstprocessing unit in accordance with the first configuration word.
 17. Themethod according to claim 16, further comprising: if the state variableindicates the first processing unit is in an unconfigured state when thereconfiguration signal is received by the first processing unit, sendingan acknowledgment signal from the first processing unit in response tothe reconfiguration signal.
 18. The method according to claim 16,further comprising: if the first processing unit is in a configuredstate when the reconfiguration signal is received by the firstprocessing unit, sending a rejection signal from the first processingunit in response to the reconfiguration signal.
 19. The method accordingto claim 16, further comprising: transmitting a differentialreconfiguration signal to the first processing unit; if the firstprocessing unit is in an unconfigured state when the differentialreconfiguration signal is received by the first processing unit,maintaining the first processing unit in an unconfigured state; and ifthe first processing unit is in a configured state, processing data withthe first processing unit in accordance with the second configurationword.
 20. The method according to claim 19, further comprising: sendingan acknowledgment in response to the differential configuration signal,if the first processing unit is in a configured state when thedifferential configuration signal is received by the first processingunit.